# Contacts (/en/realtime-media/im/build/build-core-messaging/contacts/web)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

After logging in to Chat, users can start adding contacts and chatting with each other. They can also manage these contacts, for example, by adding, retrieving and removing contacts. They can also add the specified user to the blocklist to stop receiving messages from that user.

    Agora Chat, by default, allows two users to send chat messages to each other as strangers. This means that users can chat without adding each other as a contact. If you only allow chat between contacts, you can contact [support@agora.io](mailto\:support@agora.io) to enable the friend relationship check switch. After this function is enabled, the SDK will check whether the two users trying to chat are on the contact list of each other. If no, the SDK will report error code 221.

    Agora Chat, by default, allows two users to send chat messages to each other as strangers. This means that users can chat without adding each other as a contact. If you only allow chat between contacts, you can contact [support@agora.io](mailto\:support@agora.io) to enable the friend relationship check switch. After this function is enabled, the SDK will check whether the two users trying to chat are on the contact list of each other. If no, the SDK will report error code 221.

    This page shows how to use the Chat SDK to implement contact management.

    ## Understand the tech [#understand-the-tech-6]

    The Chat SDK uses the Contact module to add, remove and manage contacts. Core methods include the following:

    * `addContact`: Adds a contact.
    * `acceptContactInvite`: Accepts the contact invitation.
    * `declineContactInvite`: Declines the contact invitation.
    * `deleteContact`: Deletes a contact.
    * `getContacts`: Retrieves a list of contacts.
    * `addEventHandler`: Adds the event handler.
    * `addUsersToBlocklist`: Adds the specified user to the block list.
    * `removeUserFromBlocklist`: Removes the specified user from the block list.
    * `getBlocklist`: Retrieves a list of blocked users from the server.

    ## Prerequisites [#prerequisites-6]

    Before proceeding, ensure that you meet the following requirements:

    * You have integrated the Chat SDK, initialized the SDK and implemented the functionality of registering accounts and login. For details, see [Chat SDK quickstart](../../get-started-sdk).
    * You understand the API call frequency limits as described in [Limitations](../limitations).

    ## Implementation [#implementation-6]

    This section shows how to manage contacts with the methods provided by the Chat SDK.

    ### Manage the contact list [#manage-the-contact-list-4]

    Use this section to understand how to send a contact invitation, listen for contact events, and accept or decline the contact invitation.

    #### Send a contact invitation [#send-a-contact-invitation-4]

    Call `addContact` to add the specified user as a contact:

    ```javascript
    const message = "Hello!";
    chatClient.addContact("username", message);
    ```

    #### Listen for contact events [#listen-for-contact-events-4]

    Use `chatClient.addEventHandler` to add the following callback events. When a user receives a contact invitation, you can accept or decline the invitation.

    ```javascript
    /**
     * msg indicates the result of triggering the callback
     */
    chatClient.addEventHandler("handlerId", {
      // Occurs when the contact invitation is received
      onContactInvited: function (msg) {},
      // Occurs when the contact is deleted
      onContactDeleted: function (msg) {},
      // Occurs when a contact is added
      onContactAdded: function (msg) {},
      // Occurs when the contact invitation is declined
      onContactRefuse: function (msg) {},
      // Occurs when the contact invitation is approved
      onContactAgreed: function (msg) {},
    });
    ```

    #### Accept or decline the contact invitation [#accept-or-decline-the-contact-invitation-4]

    After receiving `onContactInvited`, call `acceptContactInvite` or `declineContactInvite` to accept or decline the invitation.

    ```javascript
    /**
     * Accepts the contact invitation
     */
    chatClient.acceptContactInvite("username");

    /**
     * Declines the contact invitation
     */
    chatClient.declineContactInvite("username");
    ```

    #### Delete a contact [#delete-a-contact-6]

    Call `deleteContact` to delete the specified contact. The deleted user receives the `onContactDeleted` callback.

    ```javascript
    chatClient.deleteContact("username");
    ```

    #### Retrieve the contact list [#retrieve-the-contact-list-5]

    To get the contact list, you can call `getContacts`.

    ```javascript
    chatClient.getContacts().then((res) => {
      console.log(res); // res.data > ['user1', 'user2']
    });
    ```

    ### Manage the block list [#manage-the-block-list-2]

    You can add any other users to the block list, regardless of whether they are on the contact list or not. Contacts are still displayed on the contact list even if they are added to the block list. After adding users to the block list, you can still send messages to them, but will not receive messages from them as they cannot send messages or friend requests to you.

    #### Add a user to the block list [#add-a-user-to-the-block-list-2]

    Call `addUsersToBlocklist` to add the specified user to the block list.

    ```javascript
    chatClient.addUsersToBlocklist({
      name: ["user1", "user2"],
    });
    ```

    #### Remove a user from the block list [#remove-a-user-from-the-block-list-2]

    To remove the specified user from the block list, call `removeUserFromBlocklist`.

    ```javascript
    chatClient.removeUserFromBlocklist({
      name: ["user1", "user2"],
    });
    ```

    #### Retrieve the block list from the server [#retrieve-the-block-list-from-the-server-2]

    To get the block list, call `getBlocklist`.

    ```javascript
    chatClient.getBlocklist();
    ```