Feature: Implement modals (#2087)

* Implement Modals (#428)

* Socket Modal Support

* fix shareded client support

* Properly use `HasResponded` instead of `_hasResponded`

* `ModalBuilder` and `TextInputBuilder` validation.

* make orginisation more consistant.

* Rest Modals.

* Docs + add missing methods

* fix message signatures and missing abstract members

* modal changes

* um?????

* update modal docs

* update docs - again for some reason

* cleanup

* fix message signatures

* add modal commands support to interaction service

* Fix _hasResponded

* update to new unsupported standard.

* Sending modals with Interaction service.

* fix spelling in ComponentBuilder

* sending IModals when responding to interactions

* interaction service modals

* fix rest modals

* spelling and minor improvements.

* improve interaction service modal proformance

* use precompiled lambda for interaction service modals

* respect user compiled lambda choice

* changes to modals in the interaction service (more)

* support compiled lambdas in modal properties.

* modal interactions tweaks

* fix inline doc

* more modal docs

* configure responce to faild modal component

* init

* solve runtime errors

* solve build errors

* add default value parsing

* make modal info caching static

* make ModalUtils static

* add inline docs

* fix build errors

* code cleanup

* Introduce Required and Label properties as seperate attributes.

* replace internal dictionary of ModalInfo with a list

* change input building logic of modals

* update RespondWithModalAsync method

* add initial value parameter back to ModalTextInput and fix optional modal field

* add missing inline docs

* dispose the reference modal instance after building

* code cleanup on modalcommandbuilder

* Update docs/guides/int_basics/message-components/text-input.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/message-components/text-input.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_basics/modals/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_framework/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_framework/intro.md

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update docs/guides/int_framework/samples/intro/modal.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/MessageComponents/IComponentInteractionData.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/MessageComponents/TextInputComponent.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/IModalInteraction.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Interactions/Attributes/Commands/ModalInteractionAttribute.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Interactions/Attributes/Modals/RequiredInputAttribute.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.Interactions/InteractionServiceConfig.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.WebSocket/Entities/Interaction/MessageComponents/SocketMessageComponentData.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Update src/Discord.Net.WebSocket/Entities/Interaction/Modals/SocketModalData.cs

Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* update interaction service modal docs

* implements ExitOnMissingmModalField config option and adds Type field to modal info

* Add WithValue to text input builders

* Fix rare NRE on component enumeration

* Fix RequestOptions being required in some methods

* Use 'OfType' instead of 'Where'

* Remove android unsported warning

* Change publicity of properties in IInputComponeontBuilder.cs

Co-authored-by: Cenk Ergen <57065323+Cenngo@users.noreply.github.com>
Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

* Remove complex parameter ref

Co-authored-by: CottageDwellingCat <80918250+CottageDwellingCat@users.noreply.github.com>
Co-authored-by: Cenk Ergen <57065323+Cenngo@users.noreply.github.com>
Co-authored-by: Jared L <48422312+lhjt@users.noreply.github.com>

Discord.Net.code-workspace

@@ -8,16 +8,16 @@
 		"editor.rulers": [
 			120
 		],
+		"editor.insertSpaces": true,
 		"files.exclude": {
 			"**/.git": true,
 			"**/.svn": true,
 			"**/.hg": true,
 			"**/CVS": true,
 			"**/.DS_Store": true,
-			"docs/": true,
 			"**/obj": true,
 			"**/bin": true,
 			"samples/": true,
 		}
 	}
-}
+}

docs/guides/int_basics/message-components/text-input.md

@@ -0,0 +1,46 @@
+---
+uid: Guides.MessageComponents.TextInputs
+title: Text Input Components
+---
+
+# Text Input Components
+
+> [!WARNING]
+> Text input components can only be used in 
+> [modals](../modals/intro.md).
+
+Text input components are a type of MessageComponents that can only be 
+used in modals. Texts inputs can be longer (the `Paragraph`) style or 
+shorter (the `Short` style). Text inputs have a variable min and max 
+length.
+
+![A modal with short and paragraph text inputs](images/image7.png)
+
+## Creating text inputs
+Text input components can be built using the `TextInputBuilder`.
+The simplest text input can built with:
+```cs
+var tb = new TextInputBuilder()
+    .WithLabel("My Text")
+    .WithCustomId("text_input");
+```
+
+and would produce a component that looks like:
+
+![basic text input component](images/image8.png)
+
+Additional options can be specified to control the placeholder, style, 
+and min/max length of the input:
+```cs
+var tb = new TextInputBuilder()
+    .WithLabel("Labeled")
+    .WithCustomId("text_input")
+	.WithStyle(TextInputStyle.Paragraph)
+	.WithMinLength(6);
+	.WithMaxLength(42)
+	.WithRequired(true)
+	.WithPlaceholder("Consider this place held.");
+```
+
+![more advanced text input](images/image9.png)
+

docs/guides/int_basics/modals/intro.md

@@ -0,0 +1,135 @@
+---
+uid: Guides.Modals.Intro
+title: Getting Started with Modals
+---
+# Modals
+
+## Getting started with modals
+This guide will show you how to use modals and give a few examples of
+valid use cases. If your question is not covered by this guide ask in the
+[Discord.Net Discord Server](https://discord.gg/dnet).
+
+### What is a modal?
+Modals are forms bots can send when responding to interactions. Modals 
+are sent to Discord as an array of message components and converted 
+into the form layout by user's clients. Modals are required to have a
+custom id, title, and at least one component. 
+
+![Screenshot of a modal](images/image2.png)
+
+When users submit modals, your client fires the ModalSubmitted event. 
+You can get the components of the modal from the `Data.Components` property
+on the SocketModal:
+
+![Screenshot of modal data](images/image1.png) 
+
+### Using modals
+
+Lets create a simple modal with an entry field for users to
+tell us their favorite food. We can start by creating a slash
+command that will respond with the modal.
+```cs
+[SlashCommand("food", "Tell us about your favorite food!")]
+public async Task FoodPreference()
+{
+    // send a modal
+}
+```
+
+Now that we have our command set up, we need to build a modal.
+We can use the aptly named `ModalBuilder` for that:
+
+| Method          | Description                               |
+| --------------- | ----------------------------------------- |
+| `WithTitle`     | Sets the modal's title.                   |
+| `WithCustomId`  | Sets the modal's custom id.               |
+| `AddTextInput`  | Adds a `TextInputBuilder` to the modal.   |
+| `AddComponents` | Adds multiple components to the modal.    |
+| `Build`         | Builds the `ModalBuilder` into a `Modal`. |
+
+We know we need to add a text input to the modal, so let's look at that
+method's parameters.
+
+| Parameter     | Description                                |
+| ------------- | ------------------------------------------ |
+| `label`       | Sets the input's label.                    |
+| `customId`    | Sets the input's custom id.                |
+| `style`       | Sets the input's style.                    |
+| `placeholder` | Sets the input's placeholder.              |
+| `minLength`   | Sets the minimum input length.             |
+| `maxLength`   | Sets the maximum input length.             |
+| `required`    | Sets whether or not the modal is required. |
+| `value`       | Sets the input's default value.            |
+
+To make a basic text input we would only need to set the `label` and
+`customId`, but in this example we will also use the `placeholder` 
+parameter. Next we can build our modal:
+
+```cs
+var mb = new ModalBuilder()
+    .WithTitle("Fav Food")
+    .WithCustomId("food_menu")
+    .AddTextInput("What??", "food_name", placeholder:"Pizza")
+    .AddTextInput("Why??", "food_reason", TextInputStyle.Paragraph, 
+        "Kus it's so tasty");
+```
+
+Now that we have a ModalBuilder we can update our command to respond
+with the modal.
+
+```cs
+[SlashCommand("food", "Tell us about your favorite food!")]
+public async Task FoodPreference()
+{
+    var mb = new ModalBuilder()
+    .WithTitle("Fav Food")
+    .WithCustomId("food_menu")
+    .AddTextInput("What??", "food_name", placeholder:"Pizza")
+    .AddTextInput("Why??", "food_reason", TextInputStyle.Paragraph, 
+        "Kus it's so tasty");
+    
+    await Context.Interaction.RespondWithModalAsync(mb.Build());
+}
+```
+
+When we run the command, our modal should pop up:
+
+![screenshot of the above modal](images/image3.png) 
+
+### Respond to modals
+
+> [!WARNING]
+> Modals can not be sent when respoding to a modal.
+
+Once a user has submitted the modal, we need to let everyone know what
+their favorite food is. We can start by hooking a task to the client's
+`ModalSubmitted` event.
+```cs
+_client.ModalSubmitted += async modal =>
+{
+    // Get the values of components.
+    List<SocketMessageComponentData> components =
+        modal.Data.Components.ToList();
+    string food = components
+        .Where(x => x.CustomId == "food_name").First().Value;
+    string reason = components
+        .Where(x => x.CustomId == "food_reason").First().Value;
+
+    // Build the message to send.
+    string message = "hey @everyone; I just learned " + 
+        $"{modal.User.Mention}'s favorite food is " +
+        $"{food} because {reason}.";
+
+    // Specify the AllowedMentions so we don't actually ping everyone.
+    AllowedMentions mentions = new AllowedMentions();
+    mentions.AllowedTypes = AllowedMentionTypes.Users;
+
+    // Respond to the modal.
+    await modal.RespondAsync(message, allowedMentions:mentions);
+}
+```
+
+Now responding to the modal should inform everyone of our tasty 
+choices.
+
+![Response of the modal submitted event](images/image4.png)

docs/guides/int_framework/intro.md

@@ -198,6 +198,18 @@ Autocomplete commands must be parameterless methods. A valid Autocomplete comman
 
 Alternatively, you can use the [AutocompleteHandlers] to simplify this workflow.
 
+## Modals
+
+Modal commands last parameter must be an implementation of `IModal`.
+A Modal implementation would look like this:
+
+[!code-csharp[Modal Command](samples/intro/modal.cs)]
+
+> [!NOTE]
+> If you are using Modals in the interaction service it is **highly 
+> recommended** that you enable `PreCompiledLambdas` in your config
+> to prevent performance issues. 
+
 ## Interaction Context
 
 Every command module provides its commands with an execution context.

docs/guides/int_framework/samples/intro/modal.cs

@@ -0,0 +1,36 @@
+// Registers a command that will respond with a modal.
+[SlashCommand("food", "Tell us about your favorite food.")]
+public async Task Command()
+    => await Context.Interaction.RespondWithModalAsync<FoodModal>("food_menu");
+
+// Defines the modal that will be sent.
+public class FoodModal : IModal
+{
+    public string Title => "Fav Food";
+    // Strings with the ModalTextInput attribute will automatically become components.
+    [InputLabel("What??")]
+    [ModalTextInput("food_name", placeholder: "Pizza", maxLength: 20)]
+    public string Food { get; set; }
+
+    // Additional paremeters can be specified to further customize the input.
+    [InputLabel("Why??")]
+    [ModalTextInput("food_reason", TextInputStyle.Paragraph, "Kuz it's tasty", maxLength: 500)]
+    public string Reason { get; set; }
+}
+
+// Responds to the modal.
+[ModalInteraction("food_menu")]
+public async Task ModalResponce(FoodModal modal)
+{
+    // Build the message to send.
+    string message = "hey @everyone, I just learned " +
+        $"{Context.User.Mention}'s favorite food is " +
+        $"{modal.Food} because {modal.Reason}.";
+
+    // Specify the AllowedMentions so we don't actually ping everyone.
+    AllowedMentions mentions = new();
+    mentions.AllowedTypes = AllowedMentionTypes.Users;
+
+    // Respond to the modal.
+    await RespondAsync(message, allowedMentions: mentions, ephemeral: true);
+}

docs/guides/toc.yml

@@ -91,8 +91,14 @@
       topicUid: Guides.MessageComponents.Buttons
     - name: Select menus
       topicUid: Guides.MessageComponents.SelectMenus
+    - name: Text Input
+      topicUid: Guides.MessageComponents.TextInputs
     - name: Advanced Concepts
       topicUid: Guides.MessageComponents.Advanced
+- name: Modal Basics 
+  items:
+    - name: Introduction
+      topicUid: Guides.Modals.Intro
 - name: Guild Events
   items:
     - name: Introduction

src/Discord.Net.Core/Entities/Interactions/IDiscordInteraction.cs

@@ -332,5 +332,13 @@ namespace Discord
         ///     A task that represents the asynchronous operation of deferring the interaction.
         /// </returns>
         Task DeferAsync(bool ephemeral = false, RequestOptions options = null);
+
+        /// <summary>
+        ///     Responds to the interaction with a modal.
+        /// </summary>
+        /// <param name="modal">The modal to respond with.</param>
+        /// <param name="options">The request options for this <see langword="async"/> request.</param>
+        /// <returns>A task that represents the asynchronous operation of responding to the interaction.</returns>
+        Task RespondWithModalAsync(Modal modal, RequestOptions options = null);
     }
 }

src/Discord.Net.Core/Entities/Interactions/InteractionResponseType.cs

@@ -41,6 +41,11 @@ namespace Discord
         /// <summary>
         ///     Respond with a set of choices to a autocomplete interaction.
         /// </summary>
-        ApplicationCommandAutocompleteResult = 8
+        ApplicationCommandAutocompleteResult = 8,
+
+        /// <summary>
+        ///     Respond by showing the user a modal.
+        /// </summary>
+        Modal = 9,
     }
 }

src/Discord.Net.Core/Entities/Interactions/InteractionType.cs

@@ -23,6 +23,11 @@ namespace Discord
         /// <summary>
         ///     An autocomplete request sent from discord.
         /// </summary>
-        ApplicationCommandAutocomplete = 4
+        ApplicationCommandAutocomplete = 4,
+
+        /// <summary>
+        ///     A modal sent from discord.
+        /// </summary>
+        ModalSubmit = 5,
     }
 }

src/Discord.Net.Core/Entities/Interactions/MessageComponents/ComponentBuilder.cs

@@ -276,6 +276,11 @@ namespace Discord
         /// <returns>A <see cref="MessageComponent"/> that can be sent with <see cref="IMessageChannel.SendMessageAsync"/>.</returns>
         public MessageComponent Build()
         {
+            if (_actionRows?.SelectMany(x => x.Components)?.Any(x => x.Type == ComponentType.TextInput) ?? false)
+                throw new ArgumentException("TextInputComponents are not allowed in messages.", nameof(ActionRows));
+            if (_actionRows?.SelectMany(x => x.Components)?.Any(x => x.Type == ComponentType.ModalSubmit) ?? false)
+                throw new ArgumentException("ModalSubmit components are not allowed in messages.", nameof(ActionRows));
+            
             return _actionRows != null
                 ? new MessageComponent(_actionRows.Select(x => x.Build()).ToList())
                 : MessageComponent.Empty;
@@ -1093,4 +1098,248 @@ namespace Discord
             return new SelectMenuOption(Label, Value, Description, Emote, IsDefault);
         }
     }
+
+    public class TextInputBuilder
+    {
+        public const int LargestMaxLength = 4000;
+
+        /// <summary>
+        ///     Gets or sets the custom id of the current text input.
+        /// </summary>
+        /// <exception cref="ArgumentException" accessor="set"><see cref="CustomId"/> length exceeds <see cref="ComponentBuilder.MaxCustomIdLength"/></exception>
+        /// <exception cref="ArgumentException" accessor="set"><see cref="CustomId"/> length subceeds 1.</exception>
+        public string CustomId
+        {
+            get => _customId;
+            set => _customId = value?.Length switch
+            {
+                > ComponentBuilder.MaxCustomIdLength => throw new ArgumentOutOfRangeException(nameof(value), $"Custom Id length must be less or equal to {ComponentBuilder.MaxCustomIdLength}."),
+                0 => throw new ArgumentOutOfRangeException(nameof(value), "Custom Id length must be at least 1."),
+                _ => value
+            };
+        }
+
+        /// <summary>
+        ///     Gets or sets the style of the current text input.
+        /// </summary>
+        public TextInputStyle Style { get; set; } = TextInputStyle.Short;
+
+        /// <summary>
+        ///     Gets or sets the label of the current text input.
+        /// </summary>
+        public string Label { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the placeholder of the current text input.
+        /// </summary>
+        /// <exception cref="ArgumentException"><see cref="Placeholder"/> is longer than 100 characters</exception>
+        public string Placeholder
+        {
+            get => _placeholder;
+            set => _placeholder = (value?.Length ?? 0) <= 100
+                ? value
+                : throw new ArgumentException("Placeholder cannot have more than 100 characters.");
+        }
+
+        /// <summary>
+        ///     Gets or sets the minimum length of the current text input.
+        /// </summary>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="MinLength"/> is less than 0.</exception>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="MinLength"/> is greater than <see cref="LargestMaxLength"/>.</exception>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="MinLength"/> is greater than <see cref="MaxLength"/>.</exception>
+        public int? MinLength
+        {
+            get => _minLength;
+            set
+            {
+                if (value < 0)
+                    throw new ArgumentOutOfRangeException(nameof(value), $"MinLength must not be less than 0");
+                if (value > LargestMaxLength)
+                    throw new ArgumentOutOfRangeException(nameof(value), $"MinLength must not be greater than {LargestMaxLength}");
+                if (value > (MaxLength ?? LargestMaxLength))
+                    throw new ArgumentOutOfRangeException(nameof(value), $"MinLength must be less than MaxLength");
+                _minLength = value;
+            }
+        }
+
+        /// <summary>
+        ///     Gets or sets the maximum length of the current text input.
+        /// </summary>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="MaxLength"/> is less than 0.</exception>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="MaxLength"/> is greater than <see cref="LargestMaxLength"/>.</exception>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="MaxLength"/> is less than <see cref="MinLength"/>.</exception>
+        public int? MaxLength
+        {
+            get => _maxLength;
+            set
+            {
+                if (value < 0)
+                    throw new ArgumentOutOfRangeException(nameof(value), $"MaxLength must not be less than 0");
+                if (value > LargestMaxLength)
+                    throw new ArgumentOutOfRangeException(nameof(value), $"MaxLength most not be greater than {LargestMaxLength}");
+                if (value < (MinLength ?? -1))
+                    throw new ArgumentOutOfRangeException(nameof(value), $"MaxLength must be greater than MinLength ({MinLength})");
+                _maxLength = value;
+            }
+        }
+
+        /// <summary>
+        ///     Gets or sets whether the user is required to input text.
+        /// </summary>
+        public bool? Required { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the default value of the text input.
+        /// </summary>
+        /// <exception cref="ArgumentOutOfRangeException"><see cref="Value.Length"/> is less than 0.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">
+        ///     <see cref="Value.Length"/> is greater than <see cref="LargestMaxLength"/> or <see cref="MaxLength"/>.
+        /// </exception>
+        public string Value
+        {
+            get => _value;
+            set
+            {
+                if (value?.Length > (MaxLength ?? LargestMaxLength))
+                    throw new ArgumentOutOfRangeException(nameof(value), $"Value must not be longer than {MaxLength ?? LargestMaxLength}.");
+                if (value?.Length < (MinLength ?? 0))
+                    throw new ArgumentOutOfRangeException(nameof(value), $"Value must not be shorter than {MinLength}");
+                _value = value;
+            }
+        }
+
+        private string _customId;
+        private int? _maxLength;
+        private int? _minLength;
+        private string _placeholder;
+        private string _value;
+
+        /// <summary>
+        ///     Creates a new instance of a <see cref="TextInputBuilder"/>.
+        /// </summary>
+        /// <param name="label">The text input's label.</param>
+        /// <param name="style">The text input's style.</param>
+        /// <param name="customId">The text input's custom id.</param>
+        /// <param name="placeholder">The text input's placeholder.</param>
+        /// <param name="minLength">The text input's minimum length.</param>
+        /// <param name="maxLength">The text input's maximum length.</param>
+        /// <param name="required">The text input's required value.</param>
+        public TextInputBuilder (string label, string customId, TextInputStyle style = TextInputStyle.Short, string placeholder = null,
+            int? minLength = null, int? maxLength = null, bool? required = null, string value = null)
+        {
+            Label = label;
+            Style = style;
+            CustomId = customId;
+            Placeholder = placeholder;
+            MinLength = minLength;
+            MaxLength = maxLength;
+            Required = required;
+            Value = value;
+        }
+
+        /// <summary>
+        ///     Creates a new instance of a <see cref="TextInputBuilder"/>.
+        /// </summary>
+        public TextInputBuilder()
+        {
+
+        }
+
+        /// <summary>
+        ///     Sets the label of the current builder.
+        /// </summary>
+        /// <param name="label">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithLabel(string label)
+        {
+            Label = label;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the style of the current builder.
+        /// </summary>
+        /// <param name="style">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithStyle(TextInputStyle style)
+        {
+            Style = style;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the custom id of the current builder.
+        /// </summary>
+        /// <param name="customId">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithCustomId(string customId)
+        {
+            CustomId = customId;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the placeholder of the current builder.
+        /// </summary>
+        /// <param name="placeholder">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithPlaceholder(string placeholder)
+        {
+            Placeholder = placeholder;
+            return this;
+        }
+        
+        /// <summary>
+        ///     Sets the value of the current builder.
+        /// </summary>
+        /// <param name="value">The value to set</param>
+        /// <returns>The current builder.</returns>
+        public TextInputBuilder WithValue(string value)
+        {
+            Value = value;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the minimum length of the current builder.
+        /// </summary>
+        /// <param name="placeholder">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithMinLength(int minLength)
+        {
+            MinLength = minLength;
+            return this;
+        }
+        
+        /// <summary>
+        ///     Sets the maximum length of the current builder.
+        /// </summary>
+        /// <param name="placeholder">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithMaxLength(int maxLength)
+        {
+            MaxLength = maxLength;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the required value of the current builder.
+        /// </summary>
+        /// <param name="required">The value to set.</param>
+        /// <returns>The current builder. </returns>
+        public TextInputBuilder WithRequired(bool required)
+        {
+            Required = required;
+            return this;
+        }
+
+        public TextInputComponent Build()
+        {
+            if (string.IsNullOrEmpty(CustomId))
+                throw new ArgumentException("TextInputComponents must have a custom id.", nameof(CustomId));
+            if (string.IsNullOrWhiteSpace(Label))
+                throw new ArgumentException("TextInputComponents must have a label.", nameof(Label));
+            return new TextInputComponent(CustomId, Label, Placeholder, MinLength, MaxLength, Style, Required, Value);
+        }
+    }
 }

src/Discord.Net.Core/Entities/Interactions/MessageComponents/ComponentType.cs

@@ -18,6 +18,16 @@ namespace Discord
         /// <summary>
         ///     A select menu for picking from choices.
         /// </summary>
-        SelectMenu = 3
+        SelectMenu = 3,
+
+        /// <summary>
+        ///     A box for entering text.
+        /// </summary>
+        TextInput = 4,
+
+        /// <summary>
+        ///     An interaction sent when a model is submitted.
+        /// </summary>
+        ModalSubmit = 5,
     }
 }

src/Discord.Net.Core/Entities/Interactions/MessageComponents/IComponentInteractionData.cs

@@ -8,7 +8,7 @@ namespace Discord
     public interface IComponentInteractionData : IDiscordInteractionData
     {
         /// <summary>
-        ///     Gets the components Custom Id that was clicked.
+        ///     Gets the component's Custom Id that was clicked.
         /// </summary>
         string CustomId { get; }
 
@@ -21,5 +21,10 @@ namespace Discord
         ///     Gets the value(s) of a <see cref="SelectMenuComponent"/> interaction response.
         /// </summary>
         IReadOnlyCollection<string> Values { get; }
+
+        /// <summary>
+        ///     Gets the value of a <see cref="TextInputComponent"/> interaction response.
+        /// </summary>
+        public string Value { get; }
     }
 }

src/Discord.Net.Core/Entities/Interactions/MessageComponents/TextInputComponent.cs

@@ -0,0 +1,62 @@
+namespace Discord
+{
+    /// <summary>
+    ///     Respresents a <see cref="IMessageComponent"/> text input.
+    /// </summary>
+    public class TextInputComponent : IMessageComponent
+    {
+        /// <inheritdoc/>
+        public ComponentType Type => ComponentType.TextInput;
+
+        /// <inheritdoc/>
+        public string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the label of the component; this is the text shown above it.
+        /// </summary>
+        public string Label { get; }
+
+        /// <summary>
+        ///     Gets the placeholder of the component. 
+        /// </summary>
+        public string Placeholder { get; }
+
+        /// <summary>
+        ///     Gets the minimum length of the inputted text.
+        /// </summary>
+        public int? MinLength { get; }
+
+        /// <summary>
+        ///     Gets the maximum length of the inputted text.
+        /// </summary>
+        public int? MaxLength { get; }
+
+        /// <summary>
+        ///     Gets the style of the component.
+        /// </summary>
+        public TextInputStyle Style { get; }
+
+        /// <summary>
+        ///     Gets whether users are required to input text.
+        /// </summary>
+        public bool? Required { get; }
+
+        /// <summary>
+        ///     Gets the default value of the component.
+        /// </summary>
+        public string Value { get; }
+
+        internal TextInputComponent(string customId, string label, string placeholder, int? minLength, int? maxLength, 
+            TextInputStyle style, bool? required, string value)
+        {
+            CustomId = customId;
+            Label = label;
+            Placeholder = placeholder;
+            MinLength = minLength;
+            MaxLength = maxLength;
+            Style = style;
+            Required = required;
+            Value = value;
+        }
+    }
+}

src/Discord.Net.Core/Entities/Interactions/MessageComponents/TextInputStyle.cs

@@ -0,0 +1,14 @@
+namespace Discord
+{
+    public enum TextInputStyle
+    {
+        /// <summary>
+        ///     Intended for short, single-line text.
+        /// </summary>
+        Short = 1,
+        /// <summary>
+        ///     Intended for longer or multiline text.
+        /// </summary>
+        Paragraph = 2,
+    }
+}

src/Discord.Net.Core/Entities/Interactions/Modals/IModalInteraction.cs

@@ -0,0 +1,13 @@
+namespace Discord
+{
+    /// <summary>
+    ///     Represents an interaction type for Modals.
+    /// </summary>
+    public interface IModalInteraction : IDiscordInteraction
+    {
+        /// <summary>
+        ///     Gets the data received with this interaction; contains the clicked button.
+        /// </summary>
+        new IModalInteractionData Data { get; }
+    }
+}

src/Discord.Net.Core/Entities/Interactions/Modals/IModalInteractionData.cs

@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+
+namespace Discord
+{
+    /// <summary>
+    ///     Represents the data sent with the <see cref="IModalInteraction"/>.
+    /// </summary>
+    public interface IModalInteractionData : IDiscordInteractionData
+    {
+        /// <summary>
+        ///     Gets the <see cref="Modal"/>'s Custom Id.
+        /// </summary>
+        string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the <see cref="Modal"/> components submitted by the user.
+        /// </summary>
+        IReadOnlyCollection<IComponentInteractionData> Components { get; }
+    }
+}

src/Discord.Net.Core/Entities/Interactions/Modals/Modal.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    /// <summary>
+    ///     Represents a modal interaction. 
+    /// </summary>
+    public class Modal : IMessageComponent
+    {
+        /// <inheritdoc/>
+        public ComponentType Type => ComponentType.ModalSubmit;
+
+        /// <summary>
+        ///     Gets the title of the modal.
+        /// </summary>
+        public string Title { get; set; }
+
+        /// <inheritdoc/>
+        public string CustomId { get; set; }
+
+        /// <summary>
+        ///     Gets the components in the modal.
+        /// </summary>
+        public ModalComponent Component { get; set; }
+
+        internal Modal(string title, string customId, ModalComponent components)
+        {
+            Title = title;
+            CustomId = customId;
+            Component = components;
+        }
+    }
+}

src/Discord.Net.Core/Entities/Interactions/Modals/ModalBuilder.cs

@@ -0,0 +1,268 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    public class ModalBuilder
+    {
+        /// <summary>
+        ///     Gets or sets the components of the current modal.
+        /// </summary>
+        public ModalComponentBuilder Components { get; set; } = new();
+
+        /// <summary>
+        ///     Gets or sets the title of the current modal.
+        /// </summary>
+        public string Title { get; set; }
+
+        /// <summary>
+        ///     Gets or sets the custom id of the current modal.
+        /// </summary>
+        public string CustomId
+        {
+            get => _customId;
+            set => _customId = value?.Length switch
+            {
+                > ComponentBuilder.MaxCustomIdLength => throw new ArgumentOutOfRangeException(nameof(value), $"Custom Id length must be less or equal to {ComponentBuilder.MaxCustomIdLength}."),
+                0 => throw new ArgumentOutOfRangeException(nameof(value), "Custom Id length must be at least 1."),
+                _ => value
+            };
+        }
+
+        private string _customId;
+
+        public ModalBuilder() { }
+
+        /// <summary>
+        ///     Creates a new instance of a <see cref="ModalBuilder"/>
+        /// </summary>
+        /// <param name="title">The modal's title.</param>
+        /// <param name="customId">The modal's customId.</param>
+        /// <param name="components">The modal's components.</param>
+        /// <exception cref="ArgumentException">Only TextInputComponents are allowed.</exception>
+        public ModalBuilder(string title, string customId, ModalComponentBuilder components = null)
+        {
+            Title = title;
+            CustomId = customId;
+            Components = components ?? new();
+        }
+
+        /// <summary>
+        ///     Sets the title of the current modal.
+        /// </summary>
+        /// <param name="title">The value to set the title to.</param>
+        /// <returns>The current builder.</returns>
+        public ModalBuilder WithTitle(string title)
+        {
+            Title = title;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets the custom id of the current modal.
+        /// </summary>
+        /// <param name="title">The value to set the custom id to.</param>
+        /// <returns>The current builder.</returns>
+        public ModalBuilder WithCustomId(string customId)
+        {
+            CustomId = customId;
+            return this;
+        }
+        
+        /// <summary>
+        ///     Adds a component to the current builder.
+        /// </summary>
+        /// <param name="title">The component to add.</param>
+        /// <returns>The current builder.</returns>
+        public ModalBuilder AddTextInput(TextInputBuilder component)
+        {
+            Components.WithTextInput(component);
+            return this;
+        }
+
+        /// <summary>
+        ///     Adds a <see cref="TextInputBuilder"/> to the current builder.
+        /// </summary>
+        /// <param name="customId">The input's custom id.</param>
+        /// <param name="label">The input's label.</param>
+        /// <param name="placeholder">The input's placeholder text.</param>
+        /// <param name="minLength">The input's minimum length.</param>
+        /// <param name="maxLength">The input's maximum length.</param>
+        /// <param name="style">The input's style.</param>
+        /// <returns>The current builder.</returns>
+        public ModalBuilder AddTextInput(string label, string customId, TextInputStyle style = TextInputStyle.Short, 
+            string placeholder = "", int? minLength = null, int? maxLength = null, bool? required = null, string value = null)
+            => AddTextInput(new(label, customId, style, placeholder, minLength, maxLength, required, value));
+
+        /// <summary>
+        ///     Adds multiple components to the current builder.
+        /// </summary>
+        /// <param name="components">The components to add.</param>
+        /// <returns>The current builder</returns>
+        public ModalBuilder AddComponents(List<IMessageComponent> components, int row)
+        {
+            components.ForEach(x => Components.AddComponent(x, row));
+            return this;
+        }
+
+        /// <summary>
+        ///     Builds this builder into a <see cref="Modal"/>.
+        /// </summary>
+        /// <returns>A <see cref="Modal"/> with the same values as this builder.</returns>
+        /// <exception cref="ArgumentException">Only TextInputComponents are allowed.</exception>
+        /// <exception cref="ArgumentException">Modals must have a custom id.</exception>
+        /// <exception cref="ArgumentException">Modals must have a title.</exception>
+        public Modal Build()
+        {
+            if (string.IsNullOrEmpty(CustomId))
+                throw new ArgumentException("Modals must have a custom id.", nameof(CustomId));
+            if (string.IsNullOrWhiteSpace(Title))
+                throw new ArgumentException("Modals must have a title.", nameof(Title));
+            if (Components.ActionRows?.SelectMany(x => x.Components).Any(x => x.Type != ComponentType.TextInput) ?? false)
+                throw new ArgumentException($"Only TextInputComponents are allowed.", nameof(Components));
+
+            return new(Title, CustomId, Components.Build());
+        }
+    }
+
+    /// <summary>
+    ///     Represents a builder for creating a <see cref="ModalComponent"/>.
+    /// </summary>
+    public class ModalComponentBuilder
+    {
+        /// <summary>
+        ///     The max length of a <see cref="IMessageComponent.CustomId"/>.
+        /// </summary>
+        public const int MaxCustomIdLength = 100;
+
+        /// <summary>
+        ///     The max amount of rows a <see cref="ModalComponent"/> can have.
+        /// </summary>
+        public const int MaxActionRowCount = 5;
+
+        /// <summary>
+        ///     Gets or sets the Action Rows for this Component Builder.
+        /// </summary>
+        /// <exception cref="ArgumentNullException" accessor="set"><see cref="ActionRows"/> cannot be null.</exception>
+        /// <exception cref="ArgumentException" accessor="set"><see cref="ActionRows"/> count exceeds <see cref="MaxActionRowCount"/>.</exception>
+        public List<ActionRowBuilder> ActionRows
+        {
+            get => _actionRows;
+            set
+            {
+                if (value == null)
+                    throw new ArgumentNullException(nameof(value), $"{nameof(ActionRows)} cannot be null.");
+                if (value.Count > MaxActionRowCount)
+                    throw new ArgumentOutOfRangeException(nameof(value), $"Action row count must be less than or equal to {MaxActionRowCount}.");
+                _actionRows = value;
+            }
+        }
+
+        private List<ActionRowBuilder> _actionRows;
+
+        /// <summary>
+        ///     Creates a new builder from the provided list of components.
+        /// </summary>
+        /// <param name="components">The components to create the builder from.</param>
+        /// <returns>The newly created builder.</returns>
+        public static ComponentBuilder FromComponents(IReadOnlyCollection<IMessageComponent> components)
+        {
+            var builder = new ComponentBuilder();
+            for (int i = 0; i != components.Count; i++)
+            {
+                var component = components.ElementAt(i);
+                builder.AddComponent(component, i);
+            }
+            return builder;
+        }
+
+        internal void AddComponent(IMessageComponent component, int row)
+        {
+            switch (component)
+            {
+                case TextInputComponent text:
+                    WithTextInput(text.Label, text.CustomId, text.Style, text.Placeholder, text.MinLength, text.MaxLength, row);
+                    break;
+                case ActionRowComponent actionRow:
+                    foreach (var cmp in actionRow.Components)
+                        AddComponent(cmp, row);
+                    break;
+            }
+        }
+
+        /// <summary>
+        ///     Adds a <see cref="TextInputBuilder"/> to the <see cref="ComponentBuilder"/> at the specific row.
+        ///     If the row cannot accept the component then it will add it to a row that can.
+        /// </summary>
+        /// <param name="customId">The input's custom id.</param>
+        /// <param name="label">The input's label.</param>
+        /// <param name="placeholder">The input's placeholder text.</param>
+        /// <param name="minLength">The input's minimum length.</param>
+        /// <param name="maxLength">The input's maximum length.</param>
+        /// <param name="style">The input's style.</param>
+        /// <returns>The current builder.</returns>
+        public ModalComponentBuilder WithTextInput(string label, string customId, TextInputStyle style = TextInputStyle.Short, 
+            string placeholder = null, int? minLength = null, int? maxLength = null, int row = 0, bool? required = null,
+            string value = null)
+            => WithTextInput(new(label, customId, style, placeholder, minLength, maxLength, required, value), row);
+
+        /// <summary>
+        ///     Adds a <see cref="TextInputBuilder"/> to the <see cref="ModalComponentBuilder"/> at the specific row.
+        ///     If the row cannot accept the component then it will add it to a row that can.
+        /// </summary>
+        /// <param name="text">The <see cref="TextInputBuilder"> to add.</param>
+        /// <param name="row">The row to add the text input.</param>
+        /// <exception cref="InvalidOperationException">There are no more rows to add a text input to.</exception>
+        /// <exception cref="ArgumentException"><paramref name="row"/> must be less than <see cref="MaxActionRowCount"/>.</exception>
+        /// <returns>The current builder.</returns>
+        public ModalComponentBuilder WithTextInput(TextInputBuilder text, int row = 0)
+        {
+            Preconditions.LessThan(row, MaxActionRowCount, nameof(row));
+
+            var builtButton = text.Build();
+
+            if (_actionRows == null)
+            {
+                _actionRows = new List<ActionRowBuilder>
+                {
+                    new ActionRowBuilder().AddComponent(builtButton)
+                };
+            }
+            else
+            {
+                if (_actionRows.Count == row)
+                    _actionRows.Add(new ActionRowBuilder().AddComponent(builtButton));
+                else
+                {
+                    ActionRowBuilder actionRow;
+                    if (_actionRows.Count > row)
+                        actionRow = _actionRows.ElementAt(row);
+                    else
+                    {
+                        actionRow = new ActionRowBuilder();
+                        _actionRows.Add(actionRow);
+                    }
+
+                    if (actionRow.CanTakeComponent(builtButton))
+                        actionRow.AddComponent(builtButton);
+                    else if (row < MaxActionRowCount)
+                        WithTextInput(text, row + 1);
+                    else
+                        throw new InvalidOperationException($"There are no more rows to add {nameof(text)} to.");
+                }
+            }
+
+            return this;
+        }
+
+        /// <summary>
+        ///     Get a <see cref="ModalComponent"/> representing the builder.
+        /// </summary>
+        /// <returns>A <see cref="ModalComponent"/> representing the builder.</returns>
+        public ModalComponent Build()
+            => new (ActionRows?.Select(x => x.Build()).ToList());
+    }
+}

src/Discord.Net.Core/Entities/Interactions/Modals/ModalComponent.cs

@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+
+namespace Discord
+{
+    /// <summary>
+    ///     Represents a component object used in <see cref="Modal"/>s.
+    /// </summary>
+    public class ModalComponent
+    {
+        /// <summary>
+        ///     Gets the components to be used in a modal.
+        /// </summary>
+        public IReadOnlyCollection<ActionRowComponent> Components { get; }
+
+        internal ModalComponent(List<ActionRowComponent> components)
+        {
+            Components = components;
+        }
+    }
+}

src/Discord.Net.Interactions/Attributes/Commands/ModalInteractionAttribute.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Create a Modal interaction handler. CustomId represents
+    ///     the CustomId of the Modal that will be handled.
+    /// </summary>
+    /// <remarks>
+    ///     <see cref="GroupAttribute"/>s will add prefixes to this command if <see cref="IgnoreGroupNames"/> is set to <see langword="false"/>
+    ///     CustomID supports a Wild Card pattern where you can use the <see cref="InteractionServiceConfig.WildCardExpression"/> to match a set of CustomIDs.
+    /// </remarks>
+    [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
+    public sealed class ModalInteractionAttribute : Attribute
+    {
+        /// <summary>
+        ///     Gets the string to compare the Modal CustomIDs with.
+        /// </summary>
+        public string CustomId { get; }
+        
+        /// <summary>
+        ///     Gets <see langword="true"/> if <see cref="GroupAttribute"/>s will be ignored while creating this command and this method will be treated as a top level command.
+        /// </summary>
+        public bool IgnoreGroupNames { get; }
+
+        /// <summary>
+        ///     Gets the run mode this command gets executed with.
+        /// </summary>
+        public RunMode RunMode { get; }
+
+        /// <summary>
+        ///     Create a command for modal interaction handling.
+        /// </summary>
+        /// <param name="customId">String to compare the modal CustomIDs with.</param>
+        /// <param name="ignoreGroupNames">If <see langword="true"/> <see cref="GroupAttribute"/>s will be ignored while creating this command and this method will be treated as a top level command.</param>
+        /// <param name="runMode">Set the run mode of the command.</param>
+        public ModalInteractionAttribute(string customId, bool ignoreGroupNames = false, RunMode runMode = RunMode.Default)
+        {
+            CustomId = customId;
+            IgnoreGroupNames = ignoreGroupNames;
+            RunMode = runMode;
+        }
+    }
+}

src/Discord.Net.Interactions/Attributes/Modals/InputLabelAttribute.cs

@@ -0,0 +1,25 @@
+using System;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Creates a custom label for an modal input.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
+    public class InputLabelAttribute : Attribute
+    {
+        /// <summary>
+        ///     Gets the label of the input.
+        /// </summary>
+        public string Label { get; }
+
+        /// <summary>
+        ///     Creates a custom label for an modal input.
+        /// </summary>
+        /// <param name="label">The label of the input.</param>
+        public InputLabelAttribute(string label)
+        {
+            Label = label;
+        }
+    }
+}

src/Discord.Net.Interactions/Attributes/Modals/ModalInputAttribute.cs

@@ -0,0 +1,32 @@
+using System;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Mark an <see cref="IModal"/> property as a modal input field.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = false)]
+    public abstract class ModalInputAttribute : Attribute
+    {
+        /// <summary>
+        ///     Gets the custom id of the text input.
+        /// </summary>
+        public string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the type of the component.
+        /// </summary>
+        public abstract ComponentType ComponentType { get; }
+
+        /// <summary>
+        ///     Create a new <see cref="ModalInputAttribute"/>.
+        /// </summary>
+        /// <param name="label">The label of the input.</param>
+        /// <param name="customId">The custom id of the input.</param>
+        /// <param name="required">Whether the user is required to input a value.></param>
+        protected ModalInputAttribute(string customId)
+        {
+            CustomId = customId;
+        }
+    }
+}

src/Discord.Net.Interactions/Attributes/Modals/ModalTextInputAttribute.cs

@@ -0,0 +1,55 @@
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Marks a <see cref="IModal"/> property as a text input.
+    /// </summary>
+    public sealed class ModalTextInputAttribute : ModalInputAttribute
+    {
+        /// <inheritdoc/>
+        public override ComponentType ComponentType => ComponentType.TextInput;
+
+        /// <summary>
+        ///     Gets the style of the text input.
+        /// </summary>
+        public TextInputStyle Style { get; }
+
+        /// <summary>
+        ///     Gets the placeholder of the text input.
+        /// </summary>
+        public string Placeholder { get; }
+
+        /// <summary>
+        ///     Gets the minimum length of the text input.
+        /// </summary>
+        public int MinLength { get; }
+
+        /// <summary>
+        ///     Gets the maximum length of the text input.
+        /// </summary>
+        public int MaxLength { get; }
+
+        /// <summary>
+        ///     Gets the initial value to be displayed by this input.
+        /// </summary>
+        public string InitialValue { get; }
+
+        /// <summary>
+        ///     Create a new <see cref="ModalTextInputAttribute"/>.
+        /// </summary>
+        /// <param name="customId"The custom id of the text input.></param>
+        /// <param name="style">The style of the text input.</param>
+        /// <param name="placeholder">The placeholder of the text input.</param>
+        /// <param name="minLength">The minimum length of the text input's content.</param>
+        /// <param name="maxLength">The maximum length of the text input's content.</param>
+        /// <param name="initValue">The initial value to be displayed by this input.</param>
+        public ModalTextInputAttribute(string customId, TextInputStyle style = TextInputStyle.Short, string placeholder = null, int minLength = 1, int maxLength = 4000, string initValue = null)
+            : base(customId)
+        {
+            Style = style;
+            Placeholder = placeholder;
+            MinLength = minLength;
+            MaxLength = maxLength;
+            InitialValue = initValue;
+        }
+    }
+}

src/Discord.Net.Interactions/Attributes/Modals/RequiredInputAttribute.cs

@@ -0,0 +1,25 @@
+using System;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Sets the input as required or optional.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)]
+    public class RequiredInputAttribute : Attribute
+    {
+        /// <summary>
+        ///     Gets whether or not user input is required for this input.
+        /// </summary>
+        public bool IsRequired { get; }
+
+        /// <summary>
+        ///     Sets the input as required or optinal.
+        /// </summary>
+        /// <param name="isRequired">Whether or not user input is required for this input.</param>
+        public RequiredInputAttribute(bool isRequired = true)
+        {
+            IsRequired = isRequired;
+        }
+    }
+}

src/Discord.Net.Interactions/Builders/Commands/ModalCommandBuilder.cs

@@ -0,0 +1,44 @@
+using System;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents a builder for creating a <see cref="ModalCommandInfo"/>.
+    /// </summary>
+    public class ModalCommandBuilder : CommandBuilder<ModalCommandInfo, ModalCommandBuilder, ModalCommandParameterBuilder>
+    {
+        protected override ModalCommandBuilder Instance => this;
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalCommandBuilder"/>.
+        /// </summary>
+        /// <param name="module">Parent module of this modal.</param>
+        public ModalCommandBuilder(ModuleBuilder module) : base(module) { }
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalCommandBuilder"/>.
+        /// </summary>
+        /// <param name="module">Parent module of this modal.</param>
+        /// <param name="name">Name of this modal.</param>
+        /// <param name="callback">Execution callback of this modal.</param>
+        public ModalCommandBuilder(ModuleBuilder module, string name, ExecuteCallback callback) : base(module, name, callback) { }
+
+        /// <summary>
+        ///     Adds a modal parameter to the parameters collection.
+        /// </summary>
+        /// <param name="configure"><see cref="ModalCommandParameterBuilder"/> factory.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public override ModalCommandBuilder AddParameter(Action<ModalCommandParameterBuilder> configure)
+        {
+            var parameter = new ModalCommandParameterBuilder(this);
+            configure(parameter);
+            AddParameters(parameter);
+            return this;
+        }
+
+        internal override ModalCommandInfo Build(ModuleInfo module, InteractionService commandService) =>
+            new(this, module, commandService);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/Inputs/IInputComponentBuilder.cs

@@ -0,0 +1,105 @@
+using System;
+using System.Collections.Generic;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represent a builder for creating <see cref="InputComponentInfo"/>.
+    /// </summary>
+    public interface IInputComponentBuilder
+    {
+        /// <summary>
+        ///     Gets the parent modal of this input component.
+        /// </summary>
+        ModalBuilder Modal { get; }
+
+        /// <summary>
+        ///     Gets the custom id of this input component.
+        /// </summary>
+        string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the label of this input component.
+        /// </summary>
+        string Label { get; }
+
+        /// <summary>
+        ///     Gets whether this input component is required.
+        /// </summary>
+        bool IsRequired { get; }
+
+        /// <summary>
+        ///     Gets the component type of this input component.
+        /// </summary>
+        ComponentType ComponentType { get; }
+
+        /// <summary>
+        ///     Get the reference type of this input component.
+        /// </summary>
+        Type Type { get; }
+
+        /// <summary>
+        ///     Gets the default value of this input component.
+        /// </summary>
+        object DefaultValue { get; }
+
+        /// <summary>
+        ///     Gets a collection of the attributes of this component.
+        /// </summary>
+        IReadOnlyCollection<Attribute> Attributes { get; }
+
+        /// <summary>
+        ///     Sets <see cref="CustomId"/>.
+        /// </summary>
+        /// <param name="customId">New value of the <see cref="CustomId"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithCustomId(string customId);
+
+        /// <summary>
+        ///     Sets <see cref="Label"/>.
+        /// </summary>
+        /// <param name="label">New value of the <see cref="Label"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithLabel(string label);
+
+        /// <summary>
+        ///     Sets <see cref="IsRequired"/>.
+        /// </summary>
+        /// <param name="isRequired">New value of the <see cref="IsRequired"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder SetIsRequired(bool isRequired);
+
+        /// <summary>
+        ///     Sets <see cref="Type"/>.
+        /// </summary>
+        /// <param name="type">New value of the <see cref="Type"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithType(Type type);
+
+        /// <summary>
+        ///     Sets <see cref="DefaultValue"/>.
+        /// </summary>
+        /// <param name="value">New value of the <see cref="DefaultValue"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder SetDefaultValue(object value);
+
+        /// <summary>
+        ///     Adds attributes to <see cref="Attributes"/>.
+        /// </summary>
+        /// <param name="attributes">New attributes to be added to <see cref="Attributes"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        IInputComponentBuilder WithAttributes(params Attribute[] attributes);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/Inputs/InputComponentBuilder.cs

@@ -0,0 +1,164 @@
+using System;
+using System.Collections.Generic;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents the base builder class for creating <see cref="InputComponentInfo"/>.
+    /// </summary>
+    /// <typeparam name="TInfo">The <see cref="InputComponentInfo"/> this builder yields when built.</typeparam>
+    /// <typeparam name="TBuilder">Inherited <see cref="InputComponentBuilder{TInfo, TBuilder}"/> type.</typeparam>
+    public abstract class InputComponentBuilder<TInfo, TBuilder> : IInputComponentBuilder
+        where TInfo : InputComponentInfo
+        where TBuilder : InputComponentBuilder<TInfo, TBuilder>
+    {
+        private readonly List<Attribute> _attributes;
+        protected abstract TBuilder Instance { get; }
+
+        /// <inheritdoc/>
+        public ModalBuilder Modal { get; }
+
+        /// <inheritdoc/>
+        public string CustomId { get; set; }
+
+        /// <inheritdoc/>
+        public string Label { get; set; }
+
+        /// <inheritdoc/>
+        public bool IsRequired { get; set; } = true;
+
+        /// <inheritdoc/>
+        public ComponentType ComponentType { get; internal set; }
+
+        /// <inheritdoc/>
+        public Type Type { get; private set; }
+
+        /// <inheritdoc/>
+        public object DefaultValue { get; set; }
+
+        /// <inheritdoc/>
+        public IReadOnlyCollection<Attribute> Attributes => _attributes;
+
+        /// <summary>
+        ///     Creates an instance of <see cref="InputComponentBuilder{TInfo, TBuilder}"/>
+        /// </summary>
+        /// <param name="modal">Parent modal of this input component.</param>
+        public InputComponentBuilder(ModalBuilder modal)
+        {
+            Modal = modal;
+            _attributes = new();
+        }
+
+        /// <summary>
+        ///     Sets <see cref="CustomId"/>.
+        /// </summary>
+        /// <param name="customId">New value of the <see cref="CustomId"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithCustomId(string customId)
+        {
+            CustomId = customId;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Label"/>.
+        /// </summary>
+        /// <param name="label">New value of the <see cref="Label"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithLabel(string label)
+        {
+            Label = label;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="IsRequired"/>.
+        /// </summary>
+        /// <param name="isRequired">New value of the <see cref="IsRequired"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder SetIsRequired(bool isRequired)
+        {
+            IsRequired = isRequired;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="ComponentType"/>.
+        /// </summary>
+        /// <param name="componentType">New value of the <see cref="ComponentType"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithComponentType(ComponentType componentType)
+        {
+            ComponentType = componentType;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Type"/>.
+        /// </summary>
+        /// <param name="type">New value of the <see cref="Type"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithType(Type type)
+        {
+            Type = type;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="DefaultValue"/>.
+        /// </summary>
+        /// <param name="value">New value of the <see cref="DefaultValue"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder SetDefaultValue(object value)
+        {
+            DefaultValue = value;
+            return Instance;
+        }
+
+        /// <summary>
+        ///     Adds attributes to <see cref="Attributes"/>.
+        /// </summary>
+        /// <param name="attributes">New attributes to be added to <see cref="Attributes"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TBuilder WithAttributes(params Attribute[] attributes)
+        {
+            _attributes.AddRange(attributes);
+            return Instance;
+        }
+
+        internal abstract TInfo Build(ModalInfo modal);
+
+        //IInputComponentBuilder
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithCustomId(string customId) => WithCustomId(customId);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithLabel(string label) => WithCustomId(label);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithType(Type type) => WithType(type);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.SetDefaultValue(object value) => SetDefaultValue(value);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.WithAttributes(params Attribute[] attributes) => WithAttributes(attributes);
+
+        /// <inheritdoc/>
+        IInputComponentBuilder IInputComponentBuilder.SetIsRequired(bool isRequired) => SetIsRequired(isRequired);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/Inputs/TextInputComponentBuilder.cs

@@ -0,0 +1,109 @@
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents a builder for creating <see cref="TextInputComponentInfo"/>.
+    /// </summary>
+    public class TextInputComponentBuilder : InputComponentBuilder<TextInputComponentInfo, TextInputComponentBuilder>
+    {
+        protected override TextInputComponentBuilder Instance => this;
+
+        /// <summary>
+        ///     Gets and sets the style of the text input.
+        /// </summary>
+        public TextInputStyle Style { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the placeholder of the text input.
+        /// </summary>
+        public string Placeholder { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the minimum length of the text input.
+        /// </summary>
+        public int MinLength { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the maximum length of the text input.
+        /// </summary>
+        public int MaxLength { get; set; }
+
+        /// <summary>
+        ///     Gets and sets the initial value to be displayed by this input.
+        /// </summary>
+        public string InitialValue { get; set; }
+
+        /// <summary>
+        ///     Initializes a new <see cref="TextInputComponentBuilder"/>.
+        /// </summary>
+        /// <param name="modal">Parent modal of this component.</param>
+        public TextInputComponentBuilder(ModalBuilder modal) : base(modal) { }
+
+        /// <summary>
+        ///     Sets <see cref="Style"/>.
+        /// </summary>
+        /// <param name="style">New value of the <see cref="SetValue(string)"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithStyle(TextInputStyle style)
+        {
+            Style = style;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Placeholder"/>.
+        /// </summary>
+        /// <param name="placeholder">New value of the <see cref="Placeholder"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithPlaceholder(string placeholder)
+        {
+            Placeholder = placeholder;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="MinLength"/>.
+        /// </summary>
+        /// <param name="minLenght">New value of the <see cref="MinLength"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithMinLenght(int minLenght)
+        {
+            MinLength = minLenght;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="MaxLength"/>.
+        /// </summary>
+        /// <param name="maxLenght">New value of the <see cref="MaxLength"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithMaxLenght(int maxLenght)
+        {
+            MaxLength = maxLenght;
+            return this;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="InitialValue"/>.
+        /// </summary>
+        /// <param name="value">New value of the <see cref="InitialValue"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public TextInputComponentBuilder WithInitialValue(string value)
+        {
+            InitialValue = value;
+            return this;
+        }
+
+        internal override TextInputComponentInfo Build(ModalInfo modal) =>
+            new(this, modal);
+    }
+}

src/Discord.Net.Interactions/Builders/Modals/ModalBuilder.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Discord.Interactions.Builders
+{
+    /// <summary>
+    ///     Represents a builder for creating <see cref="ModalInfo"/>.
+    /// </summary>
+    public class ModalBuilder
+    {
+        internal readonly List<IInputComponentBuilder> _components;
+
+        /// <summary>
+        ///     Gets the initialization delegate for this modal.
+        /// </summary>
+        public ModalInitializer ModalInitializer { get; internal set; }
+
+        /// <summary>
+        ///     Gets the title of this modal.
+        /// </summary>
+        public string Title { get; set; }
+
+        /// <summary>
+        ///     Gets the <see cref="IModal"/> implementation used to initialize this object.
+        /// </summary>
+        public Type Type { get; }
+
+        /// <summary>
+        ///     Gets a collection of the components of this modal.
+        /// </summary>
+        public IReadOnlyCollection<IInputComponentBuilder> Components => _components;
+
+        internal ModalBuilder(Type type)
+        {
+            if (!typeof(IModal).IsAssignableFrom(type))
+                throw new ArgumentException($"Must be an implementation of {nameof(IModal)}", nameof(type));
+
+            _components = new();
+        }
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalBuilder"/>
+        /// </summary>
+        /// <param name="modalInitializer">The initialization delegate for this modal.</param>
+        public ModalBuilder(Type type, ModalInitializer modalInitializer) : this(type)
+        {
+            ModalInitializer = modalInitializer;
+        }
+
+        /// <summary>
+        ///     Sets <see cref="Title"/>.
+        /// </summary>
+        /// <param name="title">New value of the <see cref="Title"/>.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public ModalBuilder WithTitle(string title)
+        {
+            Title = title;
+            return this;
+        }
+
+        /// <summary>
+        ///     Adds text components to <see cref="TextComponents"/>.
+        /// </summary>
+        /// <param name="configure">Text Component builder factory.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public ModalBuilder AddTextComponent(Action<TextInputComponentBuilder> configure)
+        {
+            var builder = new TextInputComponentBuilder(this);
+            configure(builder);
+            _components.Add(builder);
+            return this;
+        }
+
+        internal ModalInfo Build() => new(this);
+    }
+}

src/Discord.Net.Interactions/Builders/ModuleBuilder.cs

@@ -16,6 +16,7 @@ namespace Discord.Interactions.Builders
         private readonly List<ContextCommandBuilder> _contextCommands;
         private readonly List<ComponentCommandBuilder> _componentCommands;
         private readonly List<AutocompleteCommandBuilder> _autocompleteCommands;
+        private readonly List<ModalCommandBuilder> _modalCommands;
 
         /// <summary>
         ///     Gets the underlying Interaction Service.
@@ -92,6 +93,11 @@ namespace Discord.Interactions.Builders
         /// </summary>
         public IReadOnlyList<AutocompleteCommandBuilder> AutocompleteCommands => _autocompleteCommands;
 
+        /// <summary>
+        ///     Gets a collection of the Modal Commands of this module.
+        /// </summary>
+        public IReadOnlyList<ModalCommandBuilder> ModalCommands => _modalCommands;
+
         internal TypeInfo TypeInfo { get; set; }
 
         internal ModuleBuilder (InteractionService interactionService, ModuleBuilder parent = null)
@@ -105,6 +111,7 @@ namespace Discord.Interactions.Builders
             _contextCommands = new List<ContextCommandBuilder>();
             _componentCommands = new List<ComponentCommandBuilder>();
             _autocompleteCommands = new List<AutocompleteCommandBuilder>();
+            _modalCommands = new List<ModalCommandBuilder> ();
             _preconditions = new List<PreconditionAttribute>();
         }
 
@@ -152,7 +159,7 @@ namespace Discord.Interactions.Builders
         /// <returns>
         ///     The builder instance.
         /// </returns>
-        public ModuleBuilder WithDefaultPermision (bool permission)
+        public ModuleBuilder WithDefaultPermission (bool permission)
         {
             DefaultPermission = permission;
             return this;
@@ -310,6 +317,21 @@ namespace Discord.Interactions.Builders
             configure(command);
             _autocompleteCommands.Add(command);
             return this;
+
+        }
+        
+        ///     Adds a modal command builder to <see cref="ModalCommands"/>.
+        /// </summary>
+        /// <param name="configure"><see cref="ModalCommands"/> factory.</param>
+        /// <returns>
+        ///     The builder instance.
+        /// </returns>
+        public ModuleBuilder AddModalCommand(Action<ModalCommandBuilder> configure)
+        {
+            var command = new ModalCommandBuilder(this);
+            configure(command);
+            _modalCommands.Add(command);
+            return this;
         }
 
         /// <summary>

src/Discord.Net.Interactions/Builders/ModuleClassBuilder.cs

@@ -103,6 +103,7 @@ namespace Discord.Interactions.Builders
             var validContextCommands = methods.Where(IsValidContextCommandDefinition);
             var validInteractions = methods.Where(IsValidComponentCommandDefinition);
             var validAutocompleteCommands = methods.Where(IsValidAutocompleteCommandDefinition);
+            var validModalCommands = methods.Where(IsValidModalCommanDefinition);
 
             Func<IServiceProvider, IInteractionModuleBase> createInstance = commandService._useCompiledLambda ?
                 ReflectionUtils<IInteractionModuleBase>.CreateLambdaBuilder(typeInfo, commandService) : ReflectionUtils<IInteractionModuleBase>.CreateBuilder(typeInfo, commandService);
@@ -118,6 +119,9 @@ namespace Discord.Interactions.Builders
 
             foreach(var method in validAutocompleteCommands)
                 builder.AddAutocompleteCommand(x => BuildAutocompleteCommand(x, createInstance, method, commandService, services));
+
+            foreach(var method in validModalCommands)
+                builder.AddModalCommand(x => BuildModalCommand(x, createInstance, method, commandService, services));
         }
 
         private static void BuildSubModules (ModuleBuilder parent, IEnumerable<TypeInfo> subModules, IList<TypeInfo> builtTypes, InteractionService commandService,
@@ -298,6 +302,47 @@ namespace Discord.Interactions.Builders
             builder.Callback = CreateCallback(createInstance, methodInfo, commandService);
         }
 
+        private static void BuildModalCommand(ModalCommandBuilder builder, Func<IServiceProvider, IInteractionModuleBase> createInstance, MethodInfo methodInfo,
+            InteractionService commandService, IServiceProvider services)
+        {
+            var parameters = methodInfo.GetParameters();
+
+            if (parameters.Count(x => typeof(IModal).IsAssignableFrom(x.ParameterType)) > 1)
+                throw new InvalidOperationException($"A modal command can only have one {nameof(IModal)} parameter.");
+
+            if (!parameters.All(x => x.ParameterType == typeof(string) || typeof(IModal).IsAssignableFrom(x.ParameterType)))
+                throw new InvalidOperationException($"All parameters of a modal command must be either a string or an implementation of {nameof(IModal)}");
+
+            var attributes = methodInfo.GetCustomAttributes();
+
+            builder.MethodName = methodInfo.Name;
+
+            foreach (var attribute in attributes)
+            {
+                switch (attribute)
+                {
+                    case ModalInteractionAttribute modal:
+                        {
+                            builder.Name = modal.CustomId;
+                            builder.RunMode = modal.RunMode;
+                            builder.IgnoreGroupNames = modal.IgnoreGroupNames;
+                        }
+                        break;
+                    case PreconditionAttribute precondition:
+                        builder.WithPreconditions(precondition);
+                        break;
+                    default:
+                        builder.WithAttributes(attribute);
+                        break;
+                }
+            }
+
+            foreach (var parameter in parameters)
+                builder.AddParameter(x => BuildParameter(x, parameter));
+
+            builder.Callback = CreateCallback(createInstance, methodInfo, commandService);
+        }
+
         private static ExecuteCallback CreateCallback (Func<IServiceProvider, IInteractionModuleBase> createInstance,
             MethodInfo methodInfo, InteractionService commandService)
         {
@@ -400,7 +445,9 @@ namespace Discord.Interactions.Builders
             builder.Name = Regex.Replace(builder.Name, "(?<=[a-z])(?=[A-Z])", "-").ToLower();
         }
 
-        private static void BuildParameter (CommandParameterBuilder builder, ParameterInfo paramInfo)
+        private static void BuildParameter<TInfo, TBuilder> (ParameterBuilder<TInfo, TBuilder> builder, ParameterInfo paramInfo)
+            where TInfo : class, IParameterInfo
+            where TBuilder : ParameterBuilder<TInfo, TBuilder>
         {
             var attributes = paramInfo.GetCustomAttributes();
             var paramType = paramInfo.ParameterType;
@@ -428,6 +475,84 @@ namespace Discord.Interactions.Builders
         }
         #endregion
 
+        #region Modals
+        public static ModalInfo BuildModalInfo(Type modalType)
+        {
+            if (!typeof(IModal).IsAssignableFrom(modalType))
+                throw new InvalidOperationException($"{modalType.FullName} isn't an implementation of {typeof(IModal).FullName}");
+
+            var instance = Activator.CreateInstance(modalType, false) as IModal;
+
+            try
+            {
+                var builder = new ModalBuilder(modalType)
+                {
+                    Title = instance.Title
+                };
+
+                var inputs = modalType.GetProperties().Where(IsValidModalInputDefinition);
+
+                foreach (var prop in inputs)
+                {
+                    var componentType = prop.GetCustomAttribute<ModalInputAttribute>()?.ComponentType;
+
+                    switch (componentType)
+                    {
+                        case ComponentType.TextInput:
+                            builder.AddTextComponent(x => BuildTextInput(x, prop, prop.GetValue(instance)));
+                            break;
+                        case null:
+                            throw new InvalidOperationException($"{prop.Name} of {prop.DeclaringType.Name} isn't a valid modal input field.");
+                        default:
+                            throw new InvalidOperationException($"Component type {componentType} cannot be used in modals.");
+                    }
+                }
+
+                var memberInit = ReflectionUtils<IModal>.CreateLambdaMemberInit(modalType.GetTypeInfo(), modalType.GetConstructor(Type.EmptyTypes), x => x.IsDefined(typeof(ModalInputAttribute)));
+                builder.ModalInitializer = (args) => memberInit(Array.Empty<object>(), args);
+                return builder.Build();
+            }
+            finally
+            {
+                (instance as IDisposable)?.Dispose();
+            }
+        }
+
+        private static void BuildTextInput(TextInputComponentBuilder builder, PropertyInfo propertyInfo, object defaultValue)
+        {
+            var attributes = propertyInfo.GetCustomAttributes();
+
+            builder.Label = propertyInfo.Name;
+            builder.DefaultValue = defaultValue;
+            builder.WithType(propertyInfo.PropertyType);
+
+            foreach(var attribute in attributes)
+            {
+                switch (attribute)
+                {
+                    case ModalTextInputAttribute textInput:
+                        builder.CustomId = textInput.CustomId;
+                        builder.ComponentType = textInput.ComponentType;
+                        builder.Style = textInput.Style;
+                        builder.Placeholder = textInput.Placeholder;
+                        builder.MaxLength = textInput.MaxLength;
+                        builder.MinLength = textInput.MinLength;
+                        builder.InitialValue = textInput.InitialValue;
+                        break;
+                    case RequiredInputAttribute requiredInput:
+                        builder.IsRequired = requiredInput.IsRequired;
+                        break;
+                    case InputLabelAttribute inputLabel:
+                        builder.Label = inputLabel.Label;
+                        break;
+                    default:
+                        builder.WithAttributes(attribute);
+                        break;
+                }
+            }
+        }
+        #endregion
+
         internal static bool IsValidModuleDefinition (TypeInfo typeInfo)
         {
             return ModuleTypeInfo.IsAssignableFrom(typeInfo) &&
@@ -467,5 +592,21 @@ namespace Discord.Interactions.Builders
                 !methodInfo.IsGenericMethod &&
                 methodInfo.GetParameters().Length == 0;
         }
+
+        private static bool IsValidModalCommanDefinition(MethodInfo methodInfo)
+        {
+            return methodInfo.IsDefined(typeof(ModalInteractionAttribute)) &&
+                (methodInfo.ReturnType == typeof(Task) || methodInfo.ReturnType == typeof(Task<RuntimeResult>)) &&
+                !methodInfo.IsStatic &&
+                !methodInfo.IsGenericMethod &&
+                typeof(IModal).IsAssignableFrom(methodInfo.GetParameters().Last().ParameterType);
+        }
+
+        private static bool IsValidModalInputDefinition(PropertyInfo propertyInfo)
+        {
+            return propertyInfo.SetMethod?.IsPublic == true &&
+                propertyInfo.SetMethod?.IsStatic == false &&
+                propertyInfo.IsDefined(typeof(ModalInputAttribute));
+        }
     }
 }

src/Discord.Net.Interactions/Builders/Parameters/ModalCommandParameterBuilder.cs

@@ -0,0 +1,45 @@
+using System;
+
+namespace Discord.Interactions.Builders
+{
+
+    /// <summary>
+    ///     Represents a builder for creating <see cref="ModalCommandBuilder"/>.
+    /// </summary>
+    public class ModalCommandParameterBuilder : ParameterBuilder<ModalCommandParameterInfo, ModalCommandParameterBuilder>
+    {
+        protected override ModalCommandParameterBuilder Instance => this;
+
+        /// <summary>
+        ///     Gets the built <see cref="ModalInfo"/> class for this parameter, if <see cref="IsModalParameter"/> is <see langword="true"/>.
+        /// </summary>
+        public ModalInfo Modal { get; private set; }
+
+        /// <summary>
+        ///     Gets whether or not this parameter is an <see cref="IModal"/>.
+        /// </summary>
+        public bool IsModalParameter => Modal is not null;
+
+        internal ModalCommandParameterBuilder(ICommandBuilder command) : base(command) { }
+
+        /// <summary>
+        ///     Initializes a new <see cref="ModalCommandParameterBuilder"/>.
+        /// </summary>
+        /// <param name="command">Parent command of this parameter.</param>
+        /// <param name="name">Name of this command.</param>
+        /// <param name="type">Type of this parameter.</param>
+        public ModalCommandParameterBuilder(ICommandBuilder command, string name, Type type) : base(command, name, type) { }
+
+        /// <inheritdoc/>
+        public override ModalCommandParameterBuilder SetParameterType(Type type)
+        {
+            if (typeof(IModal).IsAssignableFrom(type))
+                Modal = ModalUtils.GetOrAdd(type);
+
+            return base.SetParameterType(type);
+        }
+
+        internal override ModalCommandParameterInfo Build(ICommandInfo command) =>
+            new(this, command);
+    }
+}

src/Discord.Net.Interactions/Entities/IModal.cs

@@ -0,0 +1,13 @@
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Represents a generic <see cref="Modal"/> for use with the interaction service.
+    /// </summary>
+    public interface IModal
+    {
+        /// <summary>
+        ///     Gets the modal's title.
+        /// </summary>
+        string Title { get; }
+    }
+}

src/Discord.Net.Interactions/Extensions/IDiscordInteractionExtensions.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Discord.Interactions
+{
+    public static class IDiscordInteractionExtentions
+    {
+        /// <summary>
+        ///     Respond to an interaction with a <see cref="IModal"/>.
+        /// </summary>
+        /// <typeparam name="T">Type of the <see cref="IModal"/> implementation.</typeparam>
+        /// <param name="interaction">The interaction to respond to.</param>
+        /// <param name="options">The request options for this <see langword="async"/> request.</param>
+        /// <returns>A task that represents the asynchronous operation of responding to the interaction.</returns>
+        public static async Task RespondWithModalAsync<T>(this IDiscordInteraction interaction, string customId, RequestOptions options = null)
+            where T : class, IModal
+        {
+            if (!ModalUtils.TryGet<T>(out var modalInfo))
+                throw new ArgumentException($"{typeof(T).FullName} isn't referenced by any registered Modal Interaction Command and doesn't have a cached {typeof(ModalInfo)}");
+
+            var builder = new ModalBuilder(modalInfo.Title, customId);
+
+            foreach(var input in modalInfo.Components)
+                switch (input)
+                {
+                    case TextInputComponentInfo textComponent:
+                        builder.AddTextInput(textComponent.Label, textComponent.CustomId, textComponent.Style, textComponent.Placeholder, textComponent.IsRequired ? textComponent.MinLength : null,
+                            textComponent.MaxLength, textComponent.IsRequired, textComponent.InitialValue);
+                        break;
+                    default:
+                        throw new InvalidOperationException($"{input.GetType().FullName} isn't a valid component info class");
+                }
+
+            await interaction.RespondWithModalAsync(builder.Build(), options).ConfigureAwait(false);
+        }
+    }
+}

src/Discord.Net.Interactions/Info/Commands/ComponentCommandInfo.cs

@@ -35,7 +35,7 @@ namespace Discord.Interactions
         /// <param name="services">Services that will be used while initializing the <see cref="InteractionModuleBase{T}"/>.</param>
         /// <param name="additionalArgs">Provide additional string parameters to the method along with the auto generated parameters.</param>
         /// <returns>
-        ///     A task representing the asyncronous command execution process.
+        ///     A task representing the asynchronous command execution process.
         /// </returns>
         public async Task<IResult> ExecuteAsync(IInteractionContext context, IServiceProvider services, params string[] additionalArgs)
         {

src/Discord.Net.Interactions/Info/Commands/ModalCommandInfo.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+using System.Threading.Tasks;
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Represents the info class of an attribute based method for handling Modal Interaction events.
+    /// </summary>
+    public class ModalCommandInfo : CommandInfo<ModalCommandParameterInfo>
+    {
+        /// <summary>
+        ///     Gets the <see cref="ModalInfo"/> class for this commands <see cref="IModal"/> parameter.
+        /// </summary>
+        public ModalInfo Modal { get; }
+
+        /// <inheritdoc/>
+        public override bool SupportsWildCards => true;
+
+        /// <inheritdoc/>
+        public override IReadOnlyCollection<ModalCommandParameterInfo> Parameters { get; }
+
+        internal ModalCommandInfo(Builders.ModalCommandBuilder builder, ModuleInfo module, InteractionService commandService) : base(builder, module, commandService)
+        {
+            Parameters = builder.Parameters.Select(x => x.Build(this)).ToImmutableArray();
+            Modal = Parameters.Last().Modal;
+        }
+
+        /// <inheritdoc/>
+        public override async Task<IResult> ExecuteAsync(IInteractionContext context, IServiceProvider services)
+            => await ExecuteAsync(context, services, null).ConfigureAwait(false);
+
+        /// <summary>
+        ///     Execute this command using dependency injection.
+        /// </summary>
+        /// <param name="context">Context that will be injected to the <see cref="InteractionModuleBase{T}"/>.</param>
+        /// <param name="services">Services that will be used while initializing the <see cref="InteractionModuleBase{T}"/>.</param>
+        /// <param name="additionalArgs">Provide additional string parameters to the method along with the auto generated parameters.</param>
+        /// <returns>
+        ///     A task representing the asynchronous command execution process.
+        /// </returns>
+        public async Task<IResult> ExecuteAsync(IInteractionContext context, IServiceProvider services, params string[] additionalArgs)
+        {
+            if (context.Interaction is not IModalInteraction modalInteraction)
+                return ExecuteResult.FromError(InteractionCommandError.ParseFailed, $"Provided {nameof(IInteractionContext)} doesn't belong to a Modal Interaction.");
+
+            try
+            {
+                var args = new List<object>();
+
+                if (additionalArgs is not null)
+                    args.AddRange(additionalArgs);
+
+                var modal = Modal.CreateModal(modalInteraction, Module.CommandService._exitOnMissingModalField);
+                args.Add(modal);
+
+                return await RunAsync(context, args.ToArray(), services);
+            }
+            catch (Exception ex)
+            {
+                var result = ExecuteResult.FromError(ex);
+                await InvokeModuleEvent(context, result).ConfigureAwait(false);
+                return result;
+            }
+        }
+
+        /// <inheritdoc/>
+        protected override Task InvokeModuleEvent(IInteractionContext context, IResult result)
+            => CommandService._modalCommandExecutedEvent.InvokeAsync(this, context, result);
+
+        /// <inheritdoc/>
+        protected override string GetLogString(IInteractionContext context)
+        {
+            if (context.Guild != null)
+                return $"Modal Command: \"{base.ToString()}\" for {context.User} in {context.Guild}/{context.Channel}";
+            else
+                return $"Modal Command: \"{base.ToString()}\" for {context.User} in {context.Channel}";
+        }
+    }
+}

src/Discord.Net.Interactions/Info/InputComponents/InputComponentInfo.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Represents the base info class for <see cref="IModal"/> input components.
+    /// </summary>
+    public abstract class InputComponentInfo
+    {
+        /// <summary>
+        ///     Gets the parent modal of this component.
+        /// </summary>
+        public ModalInfo Modal { get; }
+
+        /// <summary>
+        ///     Gets the custom id of this component.
+        /// </summary>
+        public string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the label of this component.
+        /// </summary>
+        public string Label { get; }
+
+        /// <summary>
+        ///     Gets whether or not this component requires a user input.
+        /// </summary>
+        public bool IsRequired { get; }
+
+        /// <summary>
+        ///     Gets the type of this component.
+        /// </summary>
+        public ComponentType ComponentType { get; }
+
+        /// <summary>
+        ///     Gets the reference type of this component.
+        /// </summary>
+        public Type Type { get; }
+
+        /// <summary>
+        ///     Gets the default value of this component.
+        /// </summary>
+        public object DefaultValue { get; }
+
+        /// <summary>
+        ///     Gets a collection of the attributes of this command.
+        /// </summary>
+        public IReadOnlyCollection<Attribute> Attributes { get; }
+
+        protected InputComponentInfo(Builders.IInputComponentBuilder builder, ModalInfo modal)
+        {
+            Modal = modal;
+            CustomId = builder.CustomId;
+            Label = builder.Label;
+            IsRequired = builder.IsRequired;
+            ComponentType = builder.ComponentType;
+            Type = builder.Type;
+            DefaultValue = builder.DefaultValue;
+            Attributes = builder.Attributes.ToImmutableArray();
+        }
+    }
+}

src/Discord.Net.Interactions/Info/InputComponents/TextInputComponentInfo.cs

@@ -0,0 +1,42 @@
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Represents the <see cref="InputComponentInfo"/> class for <see cref="ComponentType.TextInput"/> type.
+    /// </summary>
+    public class TextInputComponentInfo : InputComponentInfo
+    {
+        /// <summary>
+        ///     Gets the style of the text input.
+        /// </summary>
+        public TextInputStyle Style { get; }
+
+        /// <summary>
+        ///     Gets the placeholder of the text input.
+        /// </summary>
+        public string Placeholder { get; }
+
+        /// <summary>
+        ///     Gets the minimum length of the text input.
+        /// </summary>
+        public int MinLength { get; }
+
+        /// <summary>
+        ///     Gets the maximum length of the text input.
+        /// </summary>
+        public int MaxLength { get; }
+
+        /// <summary>
+        ///     Gets the initial value to be displayed by this input.
+        /// </summary>
+        public string InitialValue { get; }
+
+        internal TextInputComponentInfo(Builders.TextInputComponentBuilder builder, ModalInfo modal) : base(builder, modal)
+        {
+            Style = builder.Style;
+            Placeholder = builder.Placeholder;
+            MinLength = builder.MinLength;
+            MaxLength = builder.MaxLength;
+            InitialValue = builder.InitialValue;
+        }
+    }
+}

src/Discord.Net.Interactions/Info/ModalInfo.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Represents a cached object initialization delegate.
+    /// </summary>
+    /// <param name="args">Property arguments array.</param>
+    /// <returns>
+    ///     Returns the constructed object.
+    /// </returns>
+    public delegate IModal ModalInitializer(object[] args);
+
+    /// <summary>
+    ///     Represents the info class of an <see cref="IModal"/> form.
+    /// </summary>
+    public class ModalInfo
+    {
+        internal readonly ModalInitializer _initializer;
+
+        /// <summary>
+        ///     Gets the title of this modal.
+        /// </summary>
+        public string Title { get; }
+
+        /// <summary>
+        ///     Gets the <see cref="IModal"/> implementation used to initialize this object.
+        /// </summary>
+        public Type Type { get; }
+
+        /// <summary>
+        ///     Gets a collection of the components of this modal.
+        /// </summary>
+        public IReadOnlyCollection<InputComponentInfo> Components { get; }
+
+        /// <summary>
+        ///     Gets a collection of the text components of this modal.
+        /// </summary>
+        public IReadOnlyCollection<TextInputComponentInfo> TextComponents { get; }
+
+        internal ModalInfo(Builders.ModalBuilder builder)
+        {
+            Title = builder.Title;
+            Type = builder.Type;
+            Components = builder.Components.Select(x => x switch
+            {
+                Builders.TextInputComponentBuilder textComponent => textComponent.Build(this),
+                _ => throw new InvalidOperationException($"{x.GetType().FullName} isn't a supported modal input component builder type.")
+            }).ToImmutableArray();
+
+            TextComponents = Components.OfType<TextInputComponentInfo>().ToImmutableArray();
+
+            _initializer = builder.ModalInitializer;
+        }
+
+        /// <summary>
+        ///     Creates an <see cref="IModal"/> and fills it with provided message components.
+        /// </summary>
+        /// <param name="components"><see cref="IModalInteraction"/> that will be injected into the modal.</param>
+        /// <returns>
+        ///     A <see cref="IModal"/> filled with the provided components.
+        /// </returns>
+        public IModal CreateModal(IModalInteraction modalInteraction, bool throwOnMissingField = false)
+        {
+            var args = new object[Components.Count];
+            var components = modalInteraction.Data.Components.ToList();
+
+            for (var i = 0; i < Components.Count; i++)
+            {
+                var input = Components.ElementAt(i);
+                var component = components.Find(x => x.CustomId == input.CustomId);
+
+                if (component is null)
+                {
+                    if (!throwOnMissingField)
+                        args[i] = input.DefaultValue;
+                    else
+                        throw new InvalidOperationException($"Modal interaction is missing the required field: {input.CustomId}");
+                }
+                else
+                    args[i] = component.Value;
+            }
+
+            return _initializer(args);
+        }
+    }
+}

src/Discord.Net.Interactions/Info/ModuleInfo.cs

@@ -68,6 +68,8 @@ namespace Discord.Interactions
         /// </summary>
         public IReadOnlyCollection<AutocompleteCommandInfo> AutocompleteCommands { get; }
 
+        public IReadOnlyCollection<ModalCommandInfo> ModalCommands { get; }
+
         /// <summary>
         ///     Gets the declaring type of this module, if <see cref="IsSubModule"/> is <see langword="true"/>.
         /// </summary>
@@ -112,6 +114,7 @@ namespace Discord.Interactions
             ContextCommands = BuildContextCommands(builder).ToImmutableArray();
             ComponentCommands = BuildComponentCommands(builder).ToImmutableArray();
             AutocompleteCommands = BuildAutocompleteCommands(builder).ToImmutableArray();
+            ModalCommands = BuildModalCommands(builder).ToImmutableArray();
             SubModules = BuildSubModules(builder, commandService, services).ToImmutableArray();
             Attributes = BuildAttributes(builder).ToImmutableArray();
             Preconditions = BuildPreconditions(builder).ToImmutableArray();
@@ -171,6 +174,16 @@ namespace Discord.Interactions
             return result;
         }
 
+        private IEnumerable<ModalCommandInfo> BuildModalCommands(ModuleBuilder builder)
+        {
+            var result = new List<ModalCommandInfo>();
+
+            foreach (var commandBuilder in builder.ModalCommands)
+                result.Add(commandBuilder.Build(this, CommandService));
+
+            return result;
+        }
+
         private IEnumerable<Attribute> BuildAttributes (ModuleBuilder builder)
         {
             var result = new List<Attribute>();

src/Discord.Net.Interactions/Info/Parameters/ModalCommandParameterInfo.cs

@@ -0,0 +1,28 @@
+using Discord.Interactions.Builders;
+
+namespace Discord.Interactions
+{
+    /// <summary>
+    ///     Represents the base parameter info class for <see cref="InteractionService"/> modals.
+    /// </summary>
+    public class ModalCommandParameterInfo : CommandParameterInfo
+    {
+        /// <summary>
+        ///     Gets the <see cref="ModalInfo"/> class for this parameter if <see cref="IsModalParameter"/> is true.
+        /// </summary>
+        public ModalInfo Modal { get; private set; }
+
+        /// <summary>
+        ///     Gets whether this parameter is an <see cref="IModal"/>
+        /// </summary>
+        public bool IsModalParameter => Modal is not null;
+
+        /// <inheritdoc/>
+        public new ModalCommandInfo Command => base.Command as ModalCommandInfo;
+
+        internal ModalCommandParameterInfo(ModalCommandParameterBuilder builder, ICommandInfo command) : base(builder, command)
+        {
+            Modal = builder.Modal;
+        }
+    }
+}

src/Discord.Net.Interactions/InteractionModuleBase.cs

@@ -114,6 +114,13 @@ namespace Discord.Interactions
             var response = await Context.Interaction.GetOriginalResponseAsync().ConfigureAwait(false);
             await response.DeleteAsync().ConfigureAwait(false);
         }
+        
+        /// <inheritdoc cref="IDiscordInteraction.RespondWithModalAsync(Modal, RequestOptions)"/>
+        protected virtual async Task RespondWithModalAsync(Modal modal, RequestOptions options = null) => await Context.Interaction.RespondWithModalAsync(modal);
+        
+        /// <inheritdoc cref="IDiscordInteractionExtentions.RespondWithModalAsync(IDiscordInteraction, IModal, RequestOptions)"/>
+        protected virtual async Task RespondWithModalAsync<T>(string customId, RequestOptions options = null) where T : class, IModal
+            => await Context.Interaction.RespondWithModalAsync<T>(customId, options);
 
         //IInteractionModuleBase
 

src/Discord.Net.Interactions/InteractionService.cs

@@ -53,21 +53,29 @@ namespace Discord.Interactions
         public event Func<IAutocompleteHandler, IInteractionContext, IResult, Task> AutocompleteHandlerExecuted { add { _autocompleteHandlerExecutedEvent.Add(value); } remove { _autocompleteHandlerExecutedEvent.Remove(value); } }
         internal readonly AsyncEvent<Func<IAutocompleteHandler, IInteractionContext, IResult, Task>> _autocompleteHandlerExecutedEvent = new();
 
+        /// <summary>
+        ///     Occurs when a Modal command is executed.
+        /// </summary>
+        public event Func<ModalCommandInfo, IInteractionContext, IResult, Task> ModalCommandExecuted { add { _modalCommandExecutedEvent.Add(value); } remove { _modalCommandExecutedEvent.Remove(value); } }
+        internal readonly AsyncEvent<Func<ModalCommandInfo, IInteractionContext, IResult, Task>> _modalCommandExecutedEvent = new();
+
         private readonly ConcurrentDictionary<Type, ModuleInfo> _typedModuleDefs;
         private readonly CommandMap<SlashCommandInfo> _slashCommandMap;
         private readonly ConcurrentDictionary<ApplicationCommandType, CommandMap<ContextCommandInfo>> _contextCommandMaps;
         private readonly CommandMap<ComponentCommandInfo> _componentCommandMap;
         private readonly CommandMap<AutocompleteCommandInfo> _autocompleteCommandMap;
+        private readonly CommandMap<ModalCommandInfo> _modalCommandMap;
         private readonly HashSet<ModuleInfo> _moduleDefs;
         private readonly ConcurrentDictionary<Type, TypeConverter> _typeConverters;
         private readonly ConcurrentDictionary<Type, Type> _genericTypeConverters;
         private readonly ConcurrentDictionary<Type, IAutocompleteHandler> _autocompleteHandlers = new();
+        private readonly ConcurrentDictionary<Type, ModalInfo> _modalInfos = new();
         private readonly SemaphoreSlim _lock;
         internal readonly Logger _cmdLogger;
         internal readonly LogManager _logManager;
         internal readonly Func<DiscordRestClient> _getRestClient;
 
-        internal readonly bool _throwOnError, _useCompiledLambda, _enableAutocompleteHandlers, _autoServiceScopes;
+        internal readonly bool _throwOnError, _useCompiledLambda, _enableAutocompleteHandlers, _autoServiceScopes, _exitOnMissingModalField;
         internal readonly string _wildCardExp;
         internal readonly RunMode _runMode;
         internal readonly RestResponseCallback _restResponseCallback;
@@ -98,6 +106,16 @@ namespace Discord.Interactions
         public IReadOnlyCollection<ComponentCommandInfo> ComponentCommands => _moduleDefs.SelectMany(x => x.ComponentCommands).ToList();
 
         /// <summary>
+        ///     Represents all Modal Commands loaded within <see cref="InteractionService"/>.
+        /// </summary>
+        public IReadOnlyCollection<ModalCommandInfo> ModalCommands => _moduleDefs.SelectMany(x => x.ModalCommands).ToList();
+
+        /// <summary>
+        ///     Gets a collection of the cached <see cref="ModalInfo"/> classes that are referenced in registered <see cref="ModalCommandInfo"/>s.
+        /// </summary>
+        public IReadOnlyCollection<ModalInfo> Modals => ModalUtils.Modals;
+
+        /// <summary>
         ///     Initialize a <see cref="InteractionService"/> with provided configurations.
         /// </summary>
         /// <param name="discord">The discord client.</param>
@@ -145,6 +163,7 @@ namespace Discord.Interactions
             _contextCommandMaps = new ConcurrentDictionary<ApplicationCommandType, CommandMap<ContextCommandInfo>>();
             _componentCommandMap = new CommandMap<ComponentCommandInfo>(this, config.InteractionCustomIdDelimiters);
             _autocompleteCommandMap = new CommandMap<AutocompleteCommandInfo>(this);
+            _modalCommandMap = new CommandMap<ModalCommandInfo>(this, config.InteractionCustomIdDelimiters);
 
             _getRestClient = getRestClient;
 
@@ -155,6 +174,7 @@ namespace Discord.Interactions
             _throwOnError = config.ThrowOnError;
             _wildCardExp = config.WildCardExpression;
             _useCompiledLambda = config.UseCompiledLambda;
+            _exitOnMissingModalField = config.ExitOnMissingModalField;
             _enableAutocompleteHandlers = config.EnableAutocompleteHandlers;
             _autoServiceScopes = config.AutoServiceScopes;
             _restResponseCallback = config.RestResponseCallback;
@@ -509,6 +529,9 @@ namespace Discord.Interactions
             foreach (var command in module.AutocompleteCommands)
                 _autocompleteCommandMap.AddCommand(command.GetCommandKeywords(), command);
 
+            foreach (var command in module.ModalCommands)
+                _modalCommandMap.AddCommand(command, command.IgnoreGroupNames);
+
             foreach (var subModule in module.SubModules)
                 LoadModuleInternal(subModule);
         }
@@ -654,7 +677,7 @@ namespace Discord.Interactions
         public async Task<IResult> ExecuteCommandAsync (IInteractionContext context, IServiceProvider services)
         {
             var interaction = context.Interaction;
-
+            
             return interaction switch
             {
                 ISlashCommandInteraction slashCommand => await ExecuteSlashCommandAsync(context, slashCommand, services).ConfigureAwait(false),
@@ -662,6 +685,7 @@ namespace Discord.Interactions
                 IUserCommandInteraction userCommand => await ExecuteContextCommandAsync(context, userCommand.Data.Name, ApplicationCommandType.User, services).ConfigureAwait(false),
                 IMessageCommandInteraction messageCommand => await ExecuteContextCommandAsync(context, messageCommand.Data.Name, ApplicationCommandType.Message, services).ConfigureAwait(false),
                 IAutocompleteInteraction autocomplete => await ExecuteAutocompleteAsync(context, autocomplete, services).ConfigureAwait(false),
+                IModalInteraction modalCommand => await ExecuteModalCommandAsync(context, modalCommand.Data.CustomId, services).ConfigureAwait(false),
                 _ => throw new InvalidOperationException($"{interaction.Type} interaction type cannot be executed by the Interaction service"),
             };
         }
@@ -745,6 +769,20 @@ namespace Discord.Interactions
             return await commandResult.Command.ExecuteAsync(context, services).ConfigureAwait(false);
         }
 
+        private async Task<IResult> ExecuteModalCommandAsync(IInteractionContext context, string input, IServiceProvider services)
+        {
+            var result = _modalCommandMap.GetCommand(input);
+
+            if (!result.IsSuccess)
+            {
+                await _cmdLogger.DebugAsync($"Unknown custom interaction id, skipping execution ({input.ToUpper()})");
+
+                await _componentCommandExecutedEvent.InvokeAsync(null, context, result).ConfigureAwait(false);
+                return result;
+            }
+            return await result.Command.ExecuteAsync(context, services, result.RegexCaptureGroups).ConfigureAwait(false);
+        }
+
         internal TypeConverter GetTypeConverter (Type type, IServiceProvider services = null)
         {
             if (_typeConverters.TryGetValue(type, out var specific))
@@ -819,6 +857,24 @@ namespace Discord.Interactions
             _genericTypeConverters[targetType] = converterType;
         }
 
+        /// <summary>
+        ///     Loads and caches an <see cref="ModalInfo"/> for the provided <see cref="IModal"/>.
+        /// </summary>
+        /// <typeparam name="T">Type of <see cref="IModal"/> to be loaded.</typeparam>
+        /// <returns>
+        ///     The built <see cref="ModalInfo"/> instance.
+        /// </returns>
+        /// <exception cref="InvalidOperationException"></exception>
+        public ModalInfo AddModalInfo<T>() where T : class, IModal
+        {
+            var type = typeof(T);
+
+            if (_modalInfos.ContainsKey(type))
+                throw new InvalidOperationException($"Modal type {type.FullName} already exists.");
+
+            return ModalUtils.GetOrAdd(type);
+        }
+
         internal IAutocompleteHandler GetAutocompleteHandler(Type autocompleteHandlerType, IServiceProvider services = null)
         {
             services ??= EmptyServiceProvider.Instance;

src/Discord.Net.Interactions/InteractionServiceConfig.cs

@@ -36,6 +36,9 @@ namespace Discord.Interactions
         /// <summary>
         ///     Gets or sets the option to use compiled lambda expressions to create module instances and execute commands. This method improves performance at the cost of memory.
         /// </summary>
+        /// <remarks>
+        ///     For performance reasons, if you frequently use <see cref="Modal"/>s with the service, it is highly recommended that you enable compiled lambdas.
+        /// </remarks>
         public bool UseCompiledLambda { get; set; } = false;
 
         /// <summary>
@@ -56,6 +59,11 @@ namespace Discord.Interactions
         ///     Gets or sets delegate to be used by the <see cref="InteractionService"/> when responding to a Rest based interaction.
         /// </summary>
         public RestResponseCallback RestResponseCallback { get; set; } = (ctx, str) => Task.CompletedTask;
+
+        /// <summary>
+        ///     Gets or sets whether a command execution should exit when a modal command encounters a missing modal component value.
+        /// </summary>
+        public bool ExitOnMissingModalField { get; set; } = false;
     }
 
     /// <summary>

src/Discord.Net.Interactions/Utilities/ModalUtils.cs

@@ -0,0 +1,51 @@
+using Discord.Interactions.Builders;
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+
+namespace Discord.Interactions
+{
+    internal static class ModalUtils
+    {
+        private static ConcurrentDictionary<Type, ModalInfo> _modalInfos = new();
+
+        public static IReadOnlyCollection<ModalInfo> Modals => _modalInfos.Values.ToReadOnlyCollection();
+
+        public static ModalInfo GetOrAdd(Type type)
+        {
+            if (!typeof(IModal).IsAssignableFrom(type))
+                throw new ArgumentException($"Must be an implementation of {nameof(IModal)}", nameof(type));
+
+            return _modalInfos.GetOrAdd(type, ModuleClassBuilder.BuildModalInfo(type));
+        }
+
+        public static ModalInfo GetOrAdd<T>() where T : class, IModal
+            => GetOrAdd(typeof(T));
+
+        public static bool TryGet(Type type, out ModalInfo modalInfo)
+        {
+            if (!typeof(IModal).IsAssignableFrom(type))
+                throw new ArgumentException($"Must be an implementation of {nameof(IModal)}", nameof(type));
+
+            return _modalInfos.TryGetValue(type, out modalInfo);
+        }
+
+        public static bool TryGet<T>(out ModalInfo modalInfo) where T : class, IModal
+            => TryGet(typeof(T), out modalInfo);
+
+        public static bool TryRemove(Type type, out ModalInfo modalInfo)
+        {
+            if (!typeof(IModal).IsAssignableFrom(type))
+                throw new ArgumentException($"Must be an implementation of {nameof(IModal)}", nameof(type));
+
+            return _modalInfos.TryRemove(type, out modalInfo);
+        }
+
+        public static bool TryRemove<T>(out ModalInfo modalInfo) where T : class, IModal
+            => TryRemove(typeof(T), out modalInfo);
+
+        public static void Clear() => _modalInfos.Clear();
+
+        public static int Count() => _modalInfos.Count;
+    }
+}

src/Discord.Net.Interactions/Utilities/ReflectionUtils.cs

@@ -112,6 +112,67 @@ namespace Discord.Interactions
             var parameters = constructor.GetParameters();
             var properties = GetProperties(typeInfo);
 
+            var lambda = CreateLambdaMemberInit(typeInfo, constructor);
+
+            return (services) =>
+            {
+                var args = new object[parameters.Length];
+                var props = new object[properties.Length];
+
+                for (int i = 0; i < parameters.Length; i++)
+                    args[i] = GetMember(commandService, services, parameters[i].ParameterType, typeInfo);
+
+                for (int i = 0; i < properties.Length; i++)
+                    props[i] = GetMember(commandService, services, properties[i].PropertyType, typeInfo);
+
+                var instance = lambda(args, props);
+
+                return instance;
+            };
+        }
+
+        internal static Func<object[], T> CreateLambdaConstructorInvoker(TypeInfo typeInfo)
+        {
+            var constructor = GetConstructor(typeInfo);
+            var parameters = constructor.GetParameters();
+
+            var argsExp = Expression.Parameter(typeof(object[]), "args");
+
+            var parameterExps = new Expression[parameters.Length];
+
+            for (var i = 0; i < parameters.Length; i++)
+            {
+                var indexExp = Expression.Constant(i);
+                var accessExp = Expression.ArrayIndex(argsExp, indexExp);
+                parameterExps[i] = Expression.Convert(accessExp, parameters[i].ParameterType);
+            }
+
+            var newExp = Expression.New(constructor, parameterExps);
+
+            return Expression.Lambda<Func<object[], T>>(newExp, argsExp).Compile();
+        }
+
+        /// <summary>
+        ///     Create a compiled lambda property setter.
+        /// </summary>
+        internal static Action<T, object> CreateLambdaPropertySetter(PropertyInfo propertyInfo)
+        {
+            var instanceParam = Expression.Parameter(typeof(T), "instance");
+            var valueParam = Expression.Parameter(typeof(object), "value");
+
+            var prop = Expression.Property(instanceParam, propertyInfo);
+            var assign = Expression.Assign(prop, Expression.Convert(valueParam, propertyInfo.PropertyType));
+
+            return Expression.Lambda<Action<T, object>>(assign, instanceParam, valueParam).Compile();
+        }
+
+        internal static Func<object[], object[], T> CreateLambdaMemberInit(TypeInfo typeInfo, ConstructorInfo constructor, Predicate<PropertyInfo> propertySelect = null)
+        {
+            propertySelect ??= x => true;
+
+            var parameters = constructor.GetParameters();
+            var properties = GetProperties(typeInfo).Where(x => propertySelect(x)).ToArray();
+
             var argsExp = Expression.Parameter(typeof(object[]), "args");
             var propsExp = Expression.Parameter(typeof(object[]), "props");
 
@@ -137,17 +198,8 @@ namespace Discord.Interactions
             var memberInit = Expression.MemberInit(newExp, memberExps);
             var lambda = Expression.Lambda<Func<object[], object[], T>>(memberInit, argsExp, propsExp).Compile();
 
-            return (services) =>
+            return (args, props) =>
             {
-                var args = new object[parameters.Length];
-                var props = new object[properties.Length];
-
-                for (int i = 0; i < parameters.Length; i++)
-                    args[i] = GetMember(commandService, services, parameters[i].ParameterType, typeInfo);
-
-                for (int i = 0; i < properties.Length; i++)
-                    props[i] = GetMember(commandService, services, properties[i].PropertyType, typeInfo);
-
                 var instance = lambda(args, props);
 
                 return instance;

src/Discord.Net.Rest/API/Common/ActionRowComponent.cs

@@ -21,6 +21,7 @@ namespace Discord.API
                 {
                     ComponentType.Button => new ButtonComponent(x as Discord.ButtonComponent),
                     ComponentType.SelectMenu => new SelectMenuComponent(x as Discord.SelectMenuComponent),
+                    ComponentType.TextInput => new TextInputComponent(x as Discord.TextInputComponent),
                     _ => null
                 };
             }).ToArray();

src/Discord.Net.Rest/API/Common/InteractionCallbackData.cs

@@ -24,5 +24,11 @@ namespace Discord.API
 
         [JsonProperty("choices")]
         public Optional<ApplicationCommandOptionChoice[]> Choices { get; set; }
+
+        [JsonProperty("title")]
+        public Optional<string> Title { get; set; }
+
+        [JsonProperty("custom_id")]
+        public Optional<string> CustomId { get; set; }
     }
 }

src/Discord.Net.Rest/API/Common/MessageComponentInteractionData.cs

@@ -12,5 +12,8 @@ namespace Discord.API
 
         [JsonProperty("values")]
         public Optional<string[]> Values { get; set; }
+
+        [JsonProperty("value")]
+        public Optional<string> Value { get; set; }
     }
 }

src/Discord.Net.Rest/API/Common/ModalInteractionData.cs

@@ -0,0 +1,13 @@
+using Newtonsoft.Json;
+
+namespace Discord.API
+{
+    internal class ModalInteractionData : IDiscordInteractionData
+    {
+        [JsonProperty("custom_id")]
+        public string CustomId { get; set; }
+
+        [JsonProperty("components")]
+        public API.ActionRowComponent[] Components { get; set; }
+    }
+}

src/Discord.Net.Rest/API/Common/SelectMenuComponent.cs

@@ -26,6 +26,8 @@ namespace Discord.API
         [JsonProperty("disabled")]
         public bool Disabled { get; set; }
 
+        [JsonProperty("values")]
+        public Optional<string[]> Values { get; set; }
         public SelectMenuComponent() { }
 
         public SelectMenuComponent(Discord.SelectMenuComponent component)

src/Discord.Net.Rest/API/Common/TextInputComponent.cs

@@ -0,0 +1,49 @@
+using Newtonsoft.Json;
+
+namespace Discord.API
+{
+    internal class TextInputComponent : IMessageComponent
+    {
+        [JsonProperty("type")]
+        public ComponentType Type { get; set; }
+
+        [JsonProperty("style")]
+        public TextInputStyle Style { get; set; }
+
+        [JsonProperty("custom_id")]
+        public string CustomId { get; set; }
+
+        [JsonProperty("label")]
+        public string Label { get; set; }
+
+        [JsonProperty("placeholder")]
+        public Optional<string> Placeholder { get; set; }
+
+        [JsonProperty("min_length")]
+        public Optional<int> MinLength { get; set; }
+
+        [JsonProperty("max_length")]
+        public Optional<int> MaxLength { get; set; }
+
+        [JsonProperty("value")]
+        public Optional<string> Value { get; set; }
+
+        [JsonProperty("required")]
+        public Optional<bool> Required { get; set; }
+
+        public TextInputComponent() { }
+
+        public TextInputComponent(Discord.TextInputComponent component)
+        {
+            Type = component.Type;
+            Style = component.Style;
+            CustomId = component.CustomId;
+            Label = component.Label;
+            Placeholder = component.Placeholder;
+            MinLength = component.MinLength ?? Optional<int>.Unspecified;
+            MaxLength = component.MaxLength ?? Optional<int>.Unspecified;
+            Required = component.Required ?? Optional<bool>.Unspecified;
+            Value = component.Value ?? Optional<string>.Unspecified;
+        }
+    }
+}

src/Discord.Net.Rest/Entities/Interactions/CommandBase/RestCommandBase.cs

@@ -316,5 +316,45 @@ namespace Discord.Rest
 
             return SerializePayload(response);
         }
+
+        /// <summary>
+        ///     Responds to the interaction with a modal.
+        /// </summary>
+        /// <param name="modal">The modal to respond with.</param>
+        /// <param name="options">The request options for this <see langword="async"/> request.</param>
+        /// <returns>A string that contains json to write back to the incoming http request.</returns>
+        /// <exception cref="TimeoutException"></exception>
+        /// <exception cref="InvalidOperationException"></exception>
+        public override string RespondWithModal(Modal modal, RequestOptions options = null)
+        {
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot defer an interaction after {InteractionHelper.ResponseTimeLimit} seconds of no response/acknowledgement");
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.Modal,
+                Data = new API.InteractionCallbackData
+                {
+                    CustomId = modal.CustomId,
+                    Title = modal.Title,
+                    Components = modal.Component.Components.Select(x => new Discord.API.ActionRowComponent(x)).ToArray()
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond or defer twice to the same interaction");
+                }
+            }
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+
+            return SerializePayload(response);
+        }
     }
 }

src/Discord.Net.Rest/Entities/Interactions/MessageComponents/RestMessageComponent.cs

@@ -446,6 +446,46 @@ namespace Discord.Rest
             return SerializePayload(response);
         }
 
+        /// <summary>
+        ///     Responds to the interaction with a modal.
+        /// </summary>
+        /// <param name="modal">The modal to respond with.</param>
+        /// <param name="options">The request options for this <see langword="async"/> request.</param>
+        /// <returns>A string that contains json to write back to the incoming http request.</returns>
+        /// <exception cref="TimeoutException"></exception>
+        /// <exception cref="InvalidOperationException"></exception>
+        public override string RespondWithModal(Modal modal, RequestOptions options = null)
+        {
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot defer an interaction after {InteractionHelper.ResponseTimeLimit} seconds of no response/acknowledgement");
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.Modal,
+                Data = new API.InteractionCallbackData
+                {
+                    CustomId = modal.CustomId,
+                    Title = modal.Title,
+                    Components = modal.Component.Components.Select(x => new Discord.API.ActionRowComponent(x)).ToArray()
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond or defer twice to the same interaction.");
+                }
+            }
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+
+            return SerializePayload(response);
+        }
+
         //IComponentInteraction
         /// <inheritdoc/>
         IComponentInteractionData IComponentInteraction.Data => Data;

src/Discord.Net.Rest/Entities/Interactions/MessageComponents/RestMessageComponentData.cs

@@ -27,11 +27,26 @@ namespace Discord.Rest
         /// </summary>
         public IReadOnlyCollection<string> Values { get; }
 
+        /// <inheritdoc/>
+        public string Value { get; }
+
         internal RestMessageComponentData(Model model)
         {
             CustomId = model.CustomId;
             Type = model.ComponentType;
             Values = model.Values.GetValueOrDefault();
         }
+
+        internal RestMessageComponentData(IMessageComponent component)
+        {
+            CustomId = component.CustomId;
+            Type = component.Type;
+
+            if (component is API.TextInputComponent textInput)
+                Value = textInput.Value.Value;
+
+            if (component is API.SelectMenuComponent select)
+                Values = select.Values.Value;
+        }
     }
 }

src/Discord.Net.Rest/Entities/Interactions/Modals/RestModal.cs

@@ -0,0 +1,402 @@
+using Discord.Net.Rest;
+using Discord.Rest;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+using DataModel = Discord.API.ModalInteractionData;
+using ModelBase = Discord.API.Interaction;
+
+namespace Discord.Rest
+{
+    /// <summary>
+    ///     Represents a user submitted <see cref="Modal"/>.
+    /// </summary>
+    public class RestModal : RestInteraction, IDiscordInteraction, IModalInteraction
+    {
+        internal RestModal(DiscordRestClient client, ModelBase model)
+             : base(client, model.Id)
+        {
+            var dataModel = model.Data.IsSpecified
+                ? (DataModel)model.Data.Value
+                : null;
+
+            Data = new RestModalData(dataModel);
+        }
+
+        internal new static async Task<RestModal> CreateAsync(DiscordRestClient client, ModelBase model)
+        {
+            var entity = new RestModal(client, model);
+            await entity.UpdateAsync(client, model);
+            return entity;
+        }
+        
+        private object _lock = new object();
+
+        /// <summary>
+        ///     Acknowledges this interaction with the <see cref="InteractionResponseType.DeferredChannelMessageWithSource"/>.
+        /// </summary>
+        /// <returns>
+        ///     A string that contains json to write back to the incoming http request.
+        /// </returns>
+        public override string Defer(bool ephemeral = false, RequestOptions options = null)
+        {
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot defer an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.DeferredChannelMessageWithSource,
+                Data = new API.InteractionCallbackData
+                {
+                    Flags = ephemeral ? MessageFlags.Ephemeral : Optional<MessageFlags>.Unspecified
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond or defer twice to the same interaction");
+                }
+            }
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+
+            return SerializePayload(response);
+        }
+
+        /// <summary>
+        ///     Sends a followup message for this interaction.
+        /// </summary>
+        /// <param name="text">The text of the message to be sent.</param>
+        /// <param name="embeds">A array of embeds to send with this response. Max 10.</param>
+        /// <param name="isTTS"><see langword="true"/> if the message should be read out by a text-to-speech reader, otherwise <see langword="false"/>.</param>
+        /// <param name="ephemeral"><see langword="true"/> if the response should be hidden to everyone besides the invoker of the command, otherwise <see langword="false"/>.</param>
+        /// <param name="allowedMentions">The allowed mentions for this response.</param>
+        /// <param name="options">The request options for this response.</param>
+        /// <param name="component">A <see cref="MessageComponent"/> to be sent with this response.</param>
+        /// <param name="embed">A single embed to send with this response. If this is passed alongside an array of embeds, the single embed will be ignored.</param>
+        /// <returns>
+        ///     The sent message.
+        /// </returns>
+        public override async Task<RestFollowupMessage> FollowupAsync(
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent component = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            var args = new API.Rest.CreateWebhookMessageParams
+            {
+                Content = text,
+                AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified,
+                IsTTS = isTTS,
+                Embeds = embeds.Select(x => x.ToModel()).ToArray(),
+                Components = component?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified
+            };
+
+            if (ephemeral)
+                args.Flags = MessageFlags.Ephemeral;
+
+            return await InteractionHelper.SendFollowupAsync(Discord, args, Token, Channel, options);
+        }
+
+        /// <summary>
+        ///     Sends a followup message for this interaction.
+        /// </summary>
+        /// <param name="text">The text of the message to be sent.</param>
+        /// <param name="fileStream">The file to upload.</param>
+        /// <param name="fileName">The file name of the attachment.</param>
+        /// <param name="embeds">A array of embeds to send with this response. Max 10.</param>
+        /// <param name="isTTS"><see langword="true"/> if the message should be read out by a text-to-speech reader, otherwise <see langword="false"/>.</param>
+        /// <param name="ephemeral"><see langword="true"/> if the response should be hidden to everyone besides the invoker of the command, otherwise <see langword="false"/>.</param>
+        /// <param name="allowedMentions">The allowed mentions for this response.</param>
+        /// <param name="options">The request options for this response.</param>
+        /// <param name="component">A <see cref="MessageComponent"/> to be sent with this response.</param>
+        /// <param name="embed">A single embed to send with this response. If this is passed alongside an array of embeds, the single embed will be ignored.</param>
+        /// <returns>
+        ///     The sent message.
+        /// </returns>
+        public override async Task<RestFollowupMessage> FollowupWithFileAsync(
+            Stream fileStream,
+            string fileName,
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent component = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+            Preconditions.NotNull(fileStream, nameof(fileStream), "File Stream must have data");
+            Preconditions.NotNullOrEmpty(fileName, nameof(fileName), "File Name must not be empty or null");
+
+            var args = new API.Rest.CreateWebhookMessageParams
+            {
+                Content = text,
+                AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified,
+                IsTTS = isTTS,
+                Embeds = embeds.Select(x => x.ToModel()).ToArray(),
+                Components = component?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified,
+                File = fileStream is not null ? new MultipartFile(fileStream, fileName) : Optional<MultipartFile>.Unspecified
+            };
+
+            if (ephemeral)
+                args.Flags = MessageFlags.Ephemeral;
+
+            return await InteractionHelper.SendFollowupAsync(Discord, args, Token, Channel, options);
+        }
+
+        /// <summary>
+        ///     Sends a followup message for this interaction.
+        /// </summary>
+        /// <param name="text">The text of the message to be sent.</param>
+        /// <param name="filePath">The file to upload.</param>
+        /// <param name="fileName">The file name of the attachment.</param>
+        /// <param name="embeds">A array of embeds to send with this response. Max 10.</param>
+        /// <param name="isTTS"><see langword="true"/> if the message should be read out by a text-to-speech reader, otherwise <see langword="false"/>.</param>
+        /// <param name="ephemeral"><see langword="true"/> if the response should be hidden to everyone besides the invoker of the command, otherwise <see langword="false"/>.</param>
+        /// <param name="allowedMentions">The allowed mentions for this response.</param>
+        /// <param name="options">The request options for this response.</param>
+        /// <param name="component">A <see cref="MessageComponent"/> to be sent with this response.</param>
+        /// <param name="embed">A single embed to send with this response. If this is passed alongside an array of embeds, the single embed will be ignored.</param>
+        /// <returns>
+        ///     The sent message.
+        /// </returns>
+        public override async Task<RestFollowupMessage> FollowupWithFileAsync(
+            string filePath,
+            string text = null,
+            string fileName = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent component = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+            Preconditions.NotNullOrEmpty(filePath, nameof(filePath), "Path must exist");
+
+            fileName ??= Path.GetFileName(filePath);
+            Preconditions.NotNullOrEmpty(fileName, nameof(fileName), "File Name must not be empty or null");
+
+            var args = new API.Rest.CreateWebhookMessageParams
+            {
+                Content = text,
+                AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified,
+                IsTTS = isTTS,
+                Embeds = embeds.Select(x => x.ToModel()).ToArray(),
+                Components = component?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified,
+                File = !string.IsNullOrEmpty(filePath) ? new MultipartFile(new MemoryStream(File.ReadAllBytes(filePath), false), fileName) : Optional<MultipartFile>.Unspecified
+            };
+
+            if (ephemeral)
+                args.Flags = MessageFlags.Ephemeral;
+
+            return await InteractionHelper.SendFollowupAsync(Discord, args, Token, Channel, options);
+        }
+
+        /// <summary>
+        ///     Responds to an Interaction with type <see cref="InteractionResponseType.ChannelMessageWithSource"/>.
+        /// </summary>
+        /// <param name="text">The text of the message to be sent.</param>
+        /// <param name="embeds">A array of embeds to send with this response. Max 10.</param>
+        /// <param name="isTTS"><see langword="true"/> if the message should be read out by a text-to-speech reader, otherwise <see langword="false"/>.</param>
+        /// <param name="ephemeral"><see langword="true"/> if the response should be hidden to everyone besides the invoker of the command, otherwise <see langword="false"/>.</param>
+        /// <param name="allowedMentions">The allowed mentions for this response.</param>
+        /// <param name="options">The request options for this response.</param>
+        /// <param name="component">A <see cref="MessageComponent"/> to be sent with this response.</param>
+        /// <param name="embed">A single embed to send with this response. If this is passed alongside an array of embeds, the single embed will be ignored.</param>
+        /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
+        /// <exception cref="InvalidOperationException">The parameters provided were invalid or the token was invalid.</exception>
+        /// <returns>
+        ///     A string that contains json to write back to the incoming http request.
+        /// </returns>
+        public override string Respond(
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent component = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot respond to an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            // check that user flag and user Id list are exclusive, same with role flag and role Id list
+            if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
+            {
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users) &&
+                    allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
+                {
+                    throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(allowedMentions));
+                }
+
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles) &&
+                    allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
+                {
+                    throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(allowedMentions));
+                }
+            }
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.ChannelMessageWithSource,
+                Data = new API.InteractionCallbackData
+                {
+                    Content = text,
+                    AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified,
+                    Embeds = embeds.Select(x => x.ToModel()).ToArray(),
+                    TTS = isTTS,
+                    Components = component?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified,
+                    Flags = ephemeral ? MessageFlags.Ephemeral : Optional<MessageFlags>.Unspecified
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond twice to the same interaction");
+                }
+            }
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+
+            return SerializePayload(response);
+        }
+
+        /// <inheritdoc/>
+        public override async Task<RestFollowupMessage> FollowupWithFilesAsync(
+            IEnumerable<FileAttachment> attachments,
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent components = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            foreach (var attachment in attachments)
+            {
+                Preconditions.NotNullOrEmpty(attachment.FileName, nameof(attachment.FileName), "File Name must not be empty or null");
+            }
+
+            // check that user flag and user Id list are exclusive, same with role flag and role Id list
+            if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
+            {
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users) &&
+                    allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
+                {
+                    throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(allowedMentions));
+                }
+
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles) &&
+                    allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
+                {
+                    throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(allowedMentions));
+                }
+            }
+
+            var flags = MessageFlags.None;
+
+            if (ephemeral)
+                flags |= MessageFlags.Ephemeral;
+
+            var args = new API.Rest.UploadWebhookFileParams(attachments.ToArray()) { Flags = flags, Content = text, IsTTS = isTTS, Embeds = embeds.Any() ? embeds.Select(x => x.ToModel()).ToArray() : Optional<API.Embed[]>.Unspecified, AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified, MessageComponents = components?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified };
+            return await InteractionHelper.SendFollowupAsync(Discord, args, Token, Channel, options).ConfigureAwait(false);
+        }
+
+        /// <inheritdoc/>
+        public override Task<RestFollowupMessage> FollowupWithFileAsync(
+            FileAttachment attachment,
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent components = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            return FollowupWithFilesAsync(new FileAttachment[] { attachment }, text, embeds, isTTS, ephemeral, allowedMentions, components, embed, options);
+        }
+
+        /// <inheritdoc/>
+        public override string RespondWithModal(Modal modal, RequestOptions requestOptions = null)
+            => throw new NotSupportedException("Modal interactions cannot have modal responces!");
+
+        public new RestModalData Data { get; set; }
+
+        IModalInteractionData IModalInteraction.Data => Data;
+    }
+}

src/Discord.Net.Rest/Entities/Interactions/Modals/RestModalData.cs

@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+using System.Linq;
+using System;
+using Model = Discord.API.ModalInteractionData;
+using InterationModel = Discord.API.Interaction;
+using DataModel = Discord.API.MessageComponentInteractionData;
+
+namespace Discord.Rest
+{
+    /// <summary>
+    ///     Represents data sent from a <see cref="InteractionType.ModalSubmit"/> Interaction.
+    /// </summary>
+    public class RestModalData : IComponentInteractionData, IModalInteractionData
+    {
+        /// <inheritdoc/>
+        public string CustomId { get; }
+
+        /// <summary>
+        ///     Represents the <see cref="Modal"/>s components submitted by the user.
+        /// </summary>
+        public IReadOnlyCollection<RestMessageComponentData> Components { get; }
+
+        /// <inheritdoc/>
+        public ComponentType Type => ComponentType.ModalSubmit;
+
+        /// <inheritdoc/>
+        public IReadOnlyCollection<string> Values
+            => throw new NotSupportedException("Modal interactions do not have values!");
+        
+        /// <inheritdoc/>
+        public string Value
+            => throw new NotSupportedException("Modal interactions do not have value!");
+
+        IReadOnlyCollection<IComponentInteractionData> IModalInteractionData.Components => Components;
+
+        internal RestModalData(Model model)
+        {
+            CustomId = model.CustomId;
+            Components = model.Components
+                .SelectMany(x => x.Components)
+                .Select(x => new RestMessageComponentData(x))
+                .ToArray();
+        }
+    }
+}

src/Discord.Net.Rest/Entities/Interactions/RestInteraction.cs

@@ -100,6 +100,9 @@ namespace Discord.Rest
             if (model.Type == InteractionType.ApplicationCommandAutocomplete)
                 return await RestAutocompleteInteraction.CreateAsync(client, model).ConfigureAwait(false);
 
+            if (model.Type == InteractionType.ModalSubmit)
+                return await RestModal.CreateAsync(client, model).ConfigureAwait(false);
+
             return null;
         }
 
@@ -181,6 +184,9 @@ namespace Discord.Rest
             return RestInteractionMessage.Create(Discord, model, Token, Channel);
         }
         /// <inheritdoc/>
+        public abstract string RespondWithModal(Modal modal, RequestOptions options = null);
+        
+        /// <inheritdoc/>
         public abstract string Respond(string text = null, Embed[] embeds = null, bool isTTS = false, bool ephemeral = false, AllowedMentions allowedMentions = null, MessageComponent components = null, Embed embed = null, RequestOptions options = null);
 
         /// <summary>
@@ -294,6 +300,9 @@ namespace Discord.Rest
         Task IDiscordInteraction.DeferAsync(bool ephemeral, RequestOptions options)
             => Task.FromResult(Defer(ephemeral, options));
         /// <inheritdoc/>
+        Task IDiscordInteraction.RespondWithModalAsync(Modal modal, RequestOptions options)
+            => Task.FromResult(RespondWithModal(modal, options));
+        /// <inheritdoc/>
         async Task<IUserMessage> IDiscordInteraction.FollowupAsync(string text, Embed[] embeds, bool isTTS, bool ephemeral, AllowedMentions allowedMentions,
             MessageComponent components, Embed embed, RequestOptions options)
             => await FollowupAsync(text, embeds, isTTS, ephemeral, allowedMentions, components, embed, options).ConfigureAwait(false);

src/Discord.Net.Rest/Entities/Interactions/RestPingInteraction.cs

@@ -36,6 +36,7 @@ namespace Discord.Rest
         }
 
         public override string Defer(bool ephemeral = false, RequestOptions options = null) => throw new NotSupportedException();
+        public override string RespondWithModal(Modal modal, RequestOptions options = null) => throw new NotSupportedException();
         public override string Respond(string text = null, Embed[] embeds = null, bool isTTS = false, bool ephemeral = false, AllowedMentions allowedMentions = null, MessageComponent components = null, Embed embed = null, RequestOptions options = null) => throw new NotSupportedException();
         public override Task<RestFollowupMessage> FollowupAsync(string text = null, Embed[] embeds = null, bool isTTS = false, bool ephemeral = false, AllowedMentions allowedMentions = null, MessageComponent components = null, Embed embed = null, RequestOptions options = null) => throw new NotSupportedException();
         public override Task<RestFollowupMessage> FollowupWithFileAsync(Stream fileStream, string fileName, string text = null, Embed[] embeds = null, bool isTTS = false, bool ephemeral = false, AllowedMentions allowedMentions = null, MessageComponent components = null, Embed embed = null, RequestOptions options = null) => throw new NotSupportedException();

src/Discord.Net.Rest/Entities/Interactions/SlashCommands/RestAutocompleteInteraction.cs

@@ -112,7 +112,8 @@ namespace Discord.Rest
             => throw new NotSupportedException("Autocomplete interactions don't support this method!");
         public override Task<RestFollowupMessage> FollowupWithFilesAsync(IEnumerable<FileAttachment> attachments, string text = null, Embed[] embeds = null, bool isTTS = false, bool ephemeral = false, AllowedMentions allowedMentions = null, MessageComponent components = null, Embed embed = null, RequestOptions options = null)
             => throw new NotSupportedException("Autocomplete interactions don't support this method!");
-
+        public override string RespondWithModal(Modal modal, RequestOptions options = null)
+            => throw new NotSupportedException("Autocomplete interactions don't support this method!");
 
         //IAutocompleteInteraction
         /// <inheritdoc/>

src/Discord.Net.Rest/Net/Converters/InteractionConverter.cs

@@ -56,6 +56,13 @@ namespace Discord.Net.Converters
                             interaction.Data = autocompleteData;
                         }
                         break;
+                    case InteractionType.ModalSubmit:
+                        {
+                            var modalData = new API.ModalInteractionData();
+                            serializer.Populate(result.CreateReader(), modalData);
+                            interaction.Data = modalData;
+                        }
+                        break;
                 }
             }
             else

src/Discord.Net.Rest/Net/Converters/MessageComponentConverter.cs

@@ -32,6 +32,9 @@ namespace Discord.Net.Converters
                 case ComponentType.SelectMenu:
                     messageComponent = new API.SelectMenuComponent();
                     break;
+                case ComponentType.TextInput:
+                    messageComponent = new API.TextInputComponent();
+                    break;
             }
             serializer.Populate(jsonObject.CreateReader(), messageComponent);
             return messageComponent;

src/Discord.Net.WebSocket/BaseSocketClient.Events.cs

@@ -634,6 +634,15 @@ namespace Discord.WebSocket
             remove => _autocompleteExecuted.Remove(value);
         }
         internal readonly AsyncEvent<Func<SocketAutocompleteInteraction, Task>> _autocompleteExecuted = new AsyncEvent<Func<SocketAutocompleteInteraction, Task>>();
+        /// <summary>
+        ///     Fired when a modal is submitted.
+        /// </summary>
+        public event Func<SocketModal, Task> ModalSubmitted
+        {
+            add => _modalSubmitted.Add(value);
+            remove => _modalSubmitted.Remove(value);
+        }
+        internal readonly AsyncEvent<Func<SocketModal, Task>> _modalSubmitted = new AsyncEvent<Func<SocketModal, Task>>();
 
         /// <summary>
         ///     Fired when a guild application command is created.

src/Discord.Net.WebSocket/DiscordShardedClient.cs

@@ -468,6 +468,7 @@ namespace Discord.WebSocket
             client.UserCommandExecuted += (arg) => _userCommandExecuted.InvokeAsync(arg);
             client.MessageCommandExecuted += (arg) => _messageCommandExecuted.InvokeAsync(arg);
             client.AutocompleteExecuted += (arg) => _autocompleteExecuted.InvokeAsync(arg);
+            client.ModalSubmitted += (arg) => _modalSubmitted.InvokeAsync(arg);
 
             client.ThreadUpdated += (thread1, thread2) => _threadUpdated.InvokeAsync(thread1, thread2);
             client.ThreadCreated += (thread) => _threadCreated.InvokeAsync(thread);

src/Discord.Net.WebSocket/DiscordSocketApiClient.cs

@@ -78,7 +78,7 @@ namespace Discord.API
                         if (msg != null)
                         {
 #if DEBUG_PACKETS
-                            Console.WriteLine($"<- {(GatewayOpCode)msg.Operation} [{msg.Type ?? "none"}] : {(msg.Payload as Newtonsoft.Json.Linq.JToken)?.ToString().Length}");
+                            Console.WriteLine($"<- {(GatewayOpCode)msg.Operation} [{msg.Type ?? "none"}] : {(msg.Payload as Newtonsoft.Json.Linq.JToken)}");
 #endif
 
                             await _receivedGatewayEvent.InvokeAsync((GatewayOpCode)msg.Operation, msg.Sequence, msg.Type, msg.Payload).ConfigureAwait(false);
@@ -95,7 +95,7 @@ namespace Discord.API
                     if (msg != null)
                     {
 #if DEBUG_PACKETS
-                        Console.WriteLine($"<- {(GatewayOpCode)msg.Operation} [{msg.Type ?? "none"}] : {(msg.Payload as Newtonsoft.Json.Linq.JToken)?.ToString().Length}");
+                        Console.WriteLine($"<- {(GatewayOpCode)msg.Operation} [{msg.Type ?? "none"}] : {(msg.Payload as Newtonsoft.Json.Linq.JToken)}");
 #endif
 
                         await _receivedGatewayEvent.InvokeAsync((GatewayOpCode)msg.Operation, msg.Sequence, msg.Type, msg.Payload).ConfigureAwait(false);

src/Discord.Net.WebSocket/DiscordSocketClient.cs

@@ -2274,6 +2274,9 @@ namespace Discord.WebSocket
                                         case SocketAutocompleteInteraction autocomplete:
                                             await TimedInvokeAsync(_autocompleteExecuted, nameof(AutocompleteExecuted), autocomplete).ConfigureAwait(false);
                                             break;
+                                        case SocketModal modal:
+                                            await TimedInvokeAsync(_modalSubmitted, nameof(ModalSubmitted), modal).ConfigureAwait(false);
+                                            break;
                                     }
                                 }
                                 break;

src/Discord.Net.WebSocket/Entities/Interaction/MessageComponents/SocketMessageComponent.cs

@@ -438,6 +438,41 @@ namespace Discord.WebSocket
             HasResponded = true;
         }
 
+        /// <inheritdoc/>
+        public override async Task RespondWithModalAsync(Modal modal, RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot respond to an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.Modal,
+                Data = new API.InteractionCallbackData
+                {
+                    CustomId = modal.CustomId,
+                    Title = modal.Title,
+                    Components = modal.Component.Components.Select(x => new Discord.API.ActionRowComponent(x)).ToArray()
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond twice to the same interaction");
+                }
+            }
+
+            await InteractionHelper.SendInteractionResponseAsync(Discord, response, this, Channel, options).ConfigureAwait(false);
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+        }
         //IComponentInteraction
         /// <inheritdoc/>
         IComponentInteractionData IComponentInteraction.Data => Data;

src/Discord.Net.WebSocket/Entities/Interaction/MessageComponents/SocketMessageComponentData.cs

@@ -23,11 +23,31 @@ namespace Discord.WebSocket
         /// </summary>
         public IReadOnlyCollection<string> Values { get; }
 
+        /// <summary>
+        ///     Gets the value of a <see cref="TextInputComponent"/> interaction response.
+        /// </summary>
+        public string Value { get; }
+
         internal SocketMessageComponentData(Model model)
         {
             CustomId = model.CustomId;
             Type = model.ComponentType;
             Values = model.Values.GetValueOrDefault();
+            Value = model.Value.GetValueOrDefault();
+        }
+
+        internal SocketMessageComponentData(IMessageComponent component)
+        {
+            CustomId = component.CustomId;
+            Type = component.Type;
+
+            Value = component.Type == ComponentType.TextInput
+                ? (component as API.TextInputComponent).Value.Value
+                : null;
+
+            Values = component.Type == ComponentType.SelectMenu
+                ? (component as API.SelectMenuComponent).Values.Value
+                : null;
         }
     }
 }

src/Discord.Net.WebSocket/Entities/Interaction/Modals/SocketModal.cs

@@ -0,0 +1,302 @@
+using Discord.Net.Rest;
+using Discord.Rest;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+using DataModel = Discord.API.ModalInteractionData;
+using ModelBase = Discord.API.Interaction;
+
+namespace Discord.WebSocket
+{
+    /// <summary>
+    ///     Represents a user submitted <see cref="Discord.Modal"/> received via GateWay.
+    /// </summary>
+    public class SocketModal : SocketInteraction, IDiscordInteraction, IModalInteraction
+    {
+        /// <summary>
+        ///     The data for this <see cref="Modal"/> interaction.
+        /// </summary>
+        /// <value></value>
+        public new SocketModalData Data { get; set; }
+
+        internal SocketModal(DiscordSocketClient client, ModelBase model, ISocketMessageChannel channel)
+             : base(client, model.Id, channel)
+        {
+            var dataModel = model.Data.IsSpecified
+                ? (DataModel)model.Data.Value
+                : null;
+
+            Data = new SocketModalData(dataModel);
+        }
+
+        internal new static SocketModal Create(DiscordSocketClient client, ModelBase model, ISocketMessageChannel channel)
+        {
+            var entity = new SocketModal(client, model, channel);
+            entity.Update(model);
+            return entity;
+        }
+
+        /// <inheritdoc/>
+        public override bool HasResponded { get; internal set; }
+        private object _lock = new object();
+
+        /// <inheritdoc/>
+        public override async Task RespondWithFilesAsync(
+            IEnumerable<FileAttachment> attachments,
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent components = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot respond to an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            // check that user flag and user Id list are exclusive, same with role flag and role Id list
+            if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
+            {
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users) &&
+                    allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
+                {
+                    throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(allowedMentions));
+                }
+
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles) &&
+                    allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
+                {
+                    throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(allowedMentions));
+                }
+            }
+
+            var response = new API.Rest.UploadInteractionFileParams(attachments?.ToArray())
+            {
+                Type = InteractionResponseType.ChannelMessageWithSource,
+                Content = text ?? Optional<string>.Unspecified,
+                AllowedMentions = allowedMentions != null ? allowedMentions?.ToModel() : Optional<API.AllowedMentions>.Unspecified,
+                Embeds = embeds.Any() ? embeds.Select(x => x.ToModel()).ToArray() : Optional<API.Embed[]>.Unspecified,
+                IsTTS = isTTS,
+                MessageComponents = components?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified,
+                Flags = ephemeral ? MessageFlags.Ephemeral : Optional<MessageFlags>.Unspecified
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond, update, or defer the same interaction twice");
+                }
+            }
+
+            await InteractionHelper.SendInteractionResponseAsync(Discord, response, this, Channel, options).ConfigureAwait(false);
+            HasResponded = true;
+        }
+
+        /// <inheritdoc/>
+        public override async Task RespondAsync(
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent components = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot respond to an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            // check that user flag and user Id list are exclusive, same with role flag and role Id list
+            if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
+            {
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users) &&
+                    allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
+                {
+                    throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(allowedMentions));
+                }
+
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles) &&
+                    allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
+                {
+                    throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(allowedMentions));
+                }
+            }
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.ChannelMessageWithSource,
+                Data = new API.InteractionCallbackData
+                {
+                    Content = text ?? Optional<string>.Unspecified,
+                    AllowedMentions = allowedMentions?.ToModel(),
+                    Embeds = embeds.Select(x => x.ToModel()).ToArray(),
+                    TTS = isTTS,
+                    Flags = ephemeral ? MessageFlags.Ephemeral : Optional<MessageFlags>.Unspecified,
+                    Components = components?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond, update, or defer twice to the same interaction");
+                }
+            }
+
+            await InteractionHelper.SendInteractionResponseAsync(Discord, response, this, Channel, options).ConfigureAwait(false);
+            HasResponded = true;
+        }
+
+        /// <inheritdoc/>
+        public override async Task<RestFollowupMessage> FollowupAsync(
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent components = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            var args = new API.Rest.CreateWebhookMessageParams
+            {
+                Content = text,
+                AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified,
+                IsTTS = isTTS,
+                Embeds = embeds.Select(x => x.ToModel()).ToArray(),
+                Components = components?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified
+            };
+
+            if (ephemeral)
+                args.Flags = MessageFlags.Ephemeral;
+
+            return await InteractionHelper.SendFollowupAsync(Discord.Rest, args, Token, Channel, options);
+        }
+
+        /// <inheritdoc/>
+        public override async Task<RestFollowupMessage> FollowupWithFilesAsync(
+            IEnumerable<FileAttachment> attachments,
+            string text = null,
+            Embed[] embeds = null,
+            bool isTTS = false,
+            bool ephemeral = false,
+            AllowedMentions allowedMentions = null,
+            MessageComponent components = null,
+            Embed embed = null,
+            RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            embeds ??= Array.Empty<Embed>();
+            if (embed != null)
+                embeds = new[] { embed }.Concat(embeds).ToArray();
+
+            Preconditions.AtMost(allowedMentions?.RoleIds?.Count ?? 0, 100, nameof(allowedMentions.RoleIds), "A max of 100 role Ids are allowed.");
+            Preconditions.AtMost(allowedMentions?.UserIds?.Count ?? 0, 100, nameof(allowedMentions.UserIds), "A max of 100 user Ids are allowed.");
+            Preconditions.AtMost(embeds.Length, 10, nameof(embeds), "A max of 10 embeds are allowed.");
+
+            foreach (var attachment in attachments)
+            {
+                Preconditions.NotNullOrEmpty(attachment.FileName, nameof(attachment.FileName), "File Name must not be empty or null");
+            }
+
+            // check that user flag and user Id list are exclusive, same with role flag and role Id list
+            if (allowedMentions != null && allowedMentions.AllowedTypes.HasValue)
+            {
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Users) &&
+                    allowedMentions.UserIds != null && allowedMentions.UserIds.Count > 0)
+                {
+                    throw new ArgumentException("The Users flag is mutually exclusive with the list of User Ids.", nameof(allowedMentions));
+                }
+
+                if (allowedMentions.AllowedTypes.Value.HasFlag(AllowedMentionTypes.Roles) &&
+                    allowedMentions.RoleIds != null && allowedMentions.RoleIds.Count > 0)
+                {
+                    throw new ArgumentException("The Roles flag is mutually exclusive with the list of Role Ids.", nameof(allowedMentions));
+                }
+            }
+
+            var flags = MessageFlags.None;
+
+            if (ephemeral)
+                flags |= MessageFlags.Ephemeral;
+
+            var args = new API.Rest.UploadWebhookFileParams(attachments.ToArray()) { Flags = flags, Content = text, IsTTS = isTTS, Embeds = embeds.Any() ? embeds.Select(x => x.ToModel()).ToArray() : Optional<API.Embed[]>.Unspecified, AllowedMentions = allowedMentions?.ToModel() ?? Optional<API.AllowedMentions>.Unspecified, MessageComponents = components?.Components.Select(x => new API.ActionRowComponent(x)).ToArray() ?? Optional<API.ActionRowComponent[]>.Unspecified };
+            return await InteractionHelper.SendFollowupAsync(Discord, args, Token, Channel, options).ConfigureAwait(false);
+        }
+
+        /// <inheritdoc/>
+        public override async Task DeferAsync(bool ephemeral = false, RequestOptions options = null)
+        {
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot defer an interaction after {InteractionHelper.ResponseTimeLimit} seconds of no response/acknowledgement");
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.DeferredUpdateMessage,
+                Data = ephemeral ? new API.InteractionCallbackData { Flags = MessageFlags.Ephemeral } : Optional<API.InteractionCallbackData>.Unspecified
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond or defer twice to the same interaction");
+                }
+            }
+
+            await Discord.Rest.ApiClient.CreateInteractionResponseAsync(response, Id, Token, options).ConfigureAwait(false);
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+        }
+
+        /// <inheritdoc/>
+        public override Task RespondWithModalAsync(Modal modal, RequestOptions options = null)
+            => throw new NotSupportedException("You cannot respond to a modal with a modal!");
+            
+        IModalInteractionData IModalInteraction.Data => Data;
+    }
+}

src/Discord.Net.WebSocket/Entities/Interaction/Modals/SocketModalData.cs

@@ -0,0 +1,36 @@
+using System.Collections.Generic;
+using System.Linq;
+using System;
+using Model = Discord.API.ModalInteractionData;
+using InterationModel = Discord.API.Interaction;
+using DataModel = Discord.API.MessageComponentInteractionData;
+
+namespace Discord.WebSocket
+{
+    /// <summary>
+    ///     Represents data sent from a <see cref="InteractionType.ModalSubmit"/>.
+    /// </summary>
+    public class SocketModalData : IDiscordInteractionData, IModalInteractionData
+    {
+        /// <summary>
+        ///     Gets the <see cref="Modal"/>'s Custom Id.
+        /// </summary>
+        public string CustomId { get; }
+
+        /// <summary>
+        ///     Gets the <see cref="Modal"/>'s components submitted by the user.
+        /// </summary>
+        public IReadOnlyCollection<SocketMessageComponentData> Components { get; }
+
+        internal SocketModalData(Model model)
+        {
+            CustomId = model.CustomId;
+            Components = model.Components
+                .SelectMany(x => x.Components)
+                .Select(x => new SocketMessageComponentData(x))
+                .ToArray();
+        }
+
+        IReadOnlyCollection<IComponentInteractionData> IModalInteractionData.Components => Components;
+    }
+}

src/Discord.Net.WebSocket/Entities/Interaction/SlashCommands/SocketAutocompleteInteraction.cs

@@ -100,6 +100,10 @@ namespace Discord.WebSocket
         public override Task RespondWithFilesAsync(IEnumerable<FileAttachment> attachments, string text = null, Embed[] embeds = null, bool isTTS = false, bool ephemeral = false, AllowedMentions allowedMentions = null, MessageComponent components = null, Embed embed = null, RequestOptions options = null)
             => throw new NotSupportedException("Autocomplete interactions don't support this method!");
 
+        /// <inheritdoc/>
+        public override Task RespondWithModalAsync(Modal modal, RequestOptions requestOptions = null)
+            => throw new NotSupportedException("Autocomplete interactions cannot have normal responces!");
+
         //IAutocompleteInteraction
         /// <inheritdoc/>
         IAutocompleteInteractionData IAutocompleteInteraction.Data => Data;

src/Discord.Net.WebSocket/Entities/Interaction/SocketBaseCommand/SocketCommandBase.cs

@@ -1,4 +1,3 @@
-using Discord.Net.Rest;
 using Discord.Rest;
 using System;
 using System.Collections.Generic;
@@ -135,6 +134,42 @@ namespace Discord.WebSocket
             HasResponded = true;
         }
 
+        /// <inheritdoc/>
+        public override async Task RespondWithModalAsync(Modal modal, RequestOptions options = null)
+        {
+            if (!IsValidToken)
+                throw new InvalidOperationException("Interaction token is no longer valid");
+
+            if (!InteractionHelper.CanSendResponse(this))
+                throw new TimeoutException($"Cannot respond to an interaction after {InteractionHelper.ResponseTimeLimit} seconds!");
+
+            var response = new API.InteractionResponse
+            {
+                Type = InteractionResponseType.Modal,
+                Data = new API.InteractionCallbackData
+                {
+                    CustomId = modal.CustomId,
+                    Title = modal.Title,
+                    Components = modal.Component.Components.Select(x => new Discord.API.ActionRowComponent(x)).ToArray()
+                }
+            };
+
+            lock (_lock)
+            {
+                if (HasResponded)
+                {
+                    throw new InvalidOperationException("Cannot respond twice to the same interaction");
+                }
+            }
+
+            await InteractionHelper.SendInteractionResponseAsync(Discord, response, this, Channel, options).ConfigureAwait(false);
+
+            lock (_lock)
+            {
+                HasResponded = true;
+            }
+        }
+
         public override async Task RespondWithFilesAsync(
             IEnumerable<FileAttachment> attachments,
             string text = null,

src/Discord.Net.WebSocket/Entities/Interaction/SocketInteraction.cs

@@ -108,6 +108,9 @@ namespace Discord.WebSocket
             if (model.Type == InteractionType.ApplicationCommandAutocomplete)
                 return SocketAutocompleteInteraction.Create(client, model, channel);
 
+            if (model.Type == InteractionType.ModalSubmit)
+                return SocketModal.Create(client, model, channel);
+
             return null;
         }
 
@@ -387,6 +390,13 @@ namespace Discord.WebSocket
         /// </returns>
         public abstract Task DeferAsync(bool ephemeral = false, RequestOptions options = null);
 
+        /// <summary>
+        ///     Responds to this interaction with a <see cref="Modal"/>.
+        /// </summary>
+        /// <param name="modal">The <see cref="Modal"/> to respond with.</param>
+        /// <param name="options">The request options for this <see langword="async"/> request.</param>
+        /// <returns>A task that represents the asynchronous operation of responding to the interaction.</returns>
+        public abstract Task RespondWithModalAsync(Modal modal, RequestOptions options = null);
         #endregion
 
         #region  IDiscordInteraction