Messenger for Facebook is an add-on for Facebook Messenger users, which expands Firefox's capabilities with support for this messenger. After installation, the extension is visible in the browser as a small icon, and clicking on it launches the communicator window. It offers the same features as the Messenger on the official Facebook social networking site.

It enables convenient communication with friends without the need to open the above mentioned service in your browser. The communicator is operated through a small window containing a list of contacts, call history and a set of additional options. Messenger for Facebook allows you to make standard text calls as well as voice and video chat calls.

There were also options to transfer files and photos, use stickers, animations or popular emotions. The user is also provided with options for configuring the chat window with a selected friend, notifications, the built-in search engine or the history of shared files.