diff --git a/index.d.ts b/index.d.ts
index 886b783..5525d1d 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -822,6 +822,69 @@ declare namespace WAWebJS {
     export interface PrivateChat extends Chat {
 
     }
+
+    export type GroupParticipant = {
+        id: ContactId,
+        isAdmin: boolean
+        isSuperAdmin: boolean
+    }
+
+    /** Promotes or demotes participants by IDs to regular users or admins */
+    export type ChangeParticipantsPermisions = 
+        (participantIds: Array<string>) => Promise<{ status: number }>
+
+    /** Adds or removes a list of participants by ID to the group */
+    export type ChangeGroupParticipants = 
+        (participantIds: Array<string>) => Promise<{
+            status: number;
+            participants: Array<{
+                [key: string]: {
+                    code: number
+                }
+            }>
+         } & {
+             [key: string]: number;
+         }>
+
+    export interface GroupChat extends Chat {
+        /** Group owner */
+        owner: ContactId;
+        /** Date at which the group was created */
+        createdAt: Date;
+        /** Group description */
+        description: string;
+        /** Group participants */
+        participants: Array<GroupParticipant>;
+        /** Adds a list of participants by ID to the group */
+        addParticipants: ChangeGroupParticipants;
+        /** Removes a list of participants by ID to the group */
+        removeParticipants: ChangeGroupParticipants;
+        /** Promotes participants by IDs to admins */
+        promoteParticipants: ChangeParticipantsPermisions;
+        /** Demotes participants by IDs to regular users */
+        demoteParticipants: ChangeParticipantsPermisions;
+        /** Updates the group subject */
+        setSubject: (subject: string) => Promise<void>;
+        /** Updates the group description */
+        setDescription: (description: string) => Promise<void>;
+        /** Updates the group settings to only allow admins to send messages 
+         * @param {boolean} [adminsOnly=true] Enable or disable this option 
+         * @returns {Promise<boolean>} Returns true if the setting was properly updated. This can return false if the user does not have the necessary permissions.
+         */
+        setMessagesAdminsOnly: (adminsOnly?: boolean) => Promise<boolean>;
+        /**
+         * Updates the group settings to only allow admins to edit group info (title, description, photo).
+         * @param {boolean} [adminsOnly=true] Enable or disable this option 
+         * @returns {Promise<boolean>} Returns true if the setting was properly updated. This can return false if the user does not have the necessary permissions.
+         */
+        setInfoAdminsOnly: (adminsOnly?: boolean) => Promise<boolean>;
+        /** Gets the invite code for a specific group */
+        getInviteCode: () => Promise<string>;
+        /** Invalidates the current group invite code and generates a new one */
+        revokeInvite: () => Promise<void>;
+        /** Makes the bot leave the group */
+        leave: () => Promise<void>;
+    }
 }
 
 export = WAWebJS
diff --git a/src/structures/Contact.js b/src/structures/Contact.js
index f8ec4e9..09d721c 100644
--- a/src/structures/Contact.js
+++ b/src/structures/Contact.js
@@ -2,6 +2,14 @@
 
 const Base = require('./Base');
 
+/**
+ * ID that represents a contact
+ * @typedef {Object} ContactId
+ * @property {string} server
+ * @property {string} user
+ * @property {string} _serialized
+ */
+
 /**
  * Represents a Contact on WhatsApp
  * @extends {Base}
@@ -16,7 +24,7 @@ class Contact extends Base {
     _patch(data) {
         /**
          * ID that represents the contact
-         * @type {object}
+         * @type {ContactId}
          */
         this.id = data.id;
 
diff --git a/src/structures/GroupChat.js b/src/structures/GroupChat.js
index 988c5c9..76ff151 100644
--- a/src/structures/GroupChat.js
+++ b/src/structures/GroupChat.js
@@ -2,6 +2,14 @@
 
 const Chat = require('./Chat');
 
+/**
+ * Group participant information
+ * @typedef {Object} GroupParticipant
+ * @property {ContactId} id
+ * @property {boolean} isAdmin
+ * @property {boolean} isSuperAdmin
+ */
+
 /**
  * Represents a Group Chat on WhatsApp
  * @extends {Chat}
@@ -15,6 +23,7 @@ class GroupChat extends Chat {
 
     /**
      * Gets the group owner
+     * @type {ContactId}
      */
     get owner() {
         return this.groupMetadata.owner;
@@ -38,7 +47,7 @@ class GroupChat extends Chat {
 
     /**
      * Gets the group participants
-     * @type {array}
+     * @type {Array<GroupParticipant>}
      */
     get participants() {
         return this.groupMetadata.participants;
@@ -47,6 +56,7 @@ class GroupChat extends Chat {
     /**
      * Adds a list of participants by ID to the group
      * @param {Array<string>} participantIds 
+     * @returns {Promise<Object>}
      */
     async addParticipants(participantIds) {
         return await this.client.pupPage.evaluate((chatId, participantIds) => {
@@ -57,6 +67,7 @@ class GroupChat extends Chat {
     /**
      * Removes a list of participants by ID to the group
      * @param {Array<string>} participantIds 
+     * @returns {Promise<Object>}
      */
     async removeParticipants(participantIds) {
         return await this.client.pupPage.evaluate((chatId, participantIds) => {
@@ -67,6 +78,7 @@ class GroupChat extends Chat {
     /**
      * Promotes participants by IDs to admins
      * @param {Array<string>} participantIds 
+     * @returns {Promise<{ status: number }>} Object with status code indicating if the operation was successful
      */
     async promoteParticipants(participantIds) {
         return await this.client.pupPage.evaluate((chatId, participantIds) => {
@@ -77,6 +89,7 @@ class GroupChat extends Chat {
     /**
      * Demotes participants by IDs to regular users
      * @param {Array<string>} participantIds 
+     * @returns {Promise<{ status: number }>} Object with status code indicating if the operation was successful
      */
     async demoteParticipants(participantIds) {
         return await this.client.pupPage.evaluate((chatId, participantIds) => {
@@ -87,6 +100,7 @@ class GroupChat extends Chat {
     /**
      * Updates the group subject
      * @param {string} subject 
+     * @returns {Promise} 
      */
     async setSubject(subject) {
         let res = await this.client.pupPage.evaluate((chatId, subject) => {
@@ -101,6 +115,7 @@ class GroupChat extends Chat {
     /**
      * Updates the group description
      * @param {string} description 
+     * @returns {Promise} 
      */
     async setDescription(description) {
         let res = await this.client.pupPage.evaluate((chatId, description) => {
@@ -147,6 +162,7 @@ class GroupChat extends Chat {
 
     /**
      * Gets the invite code for a specific group
+     * @returns {Promise<string>} Group's invite code
      */
     async getInviteCode() {
         let res = await this.client.pupPage.evaluate(chatId => {
@@ -162,6 +178,7 @@ class GroupChat extends Chat {
     
     /**
      * Invalidates the current group invite code and generates a new one
+     * @returns {Promise}
      */
     async revokeInvite() {
         return await this.client.pupPage.evaluate(chatId => {
@@ -171,6 +188,7 @@ class GroupChat extends Chat {
 
     /**
      * Makes the bot leave the group
+     * @returns {Promise}
      */
     async leave() {
         return await this.client.pupPage.evaluate(chatId => {