Facebook Messenger is a cross-platform mobile app that allows you to communicate with your Facebook contacts through instant messaging, voice, and video calls. Facebook Messenger is available for all major mobile OS platforms including iOS, Windows Phone, and Android. Furthermore, it also exists as a web-based client for PC and Mac.
Sign-up to the Facebook Messenger Web Client
Facebook Messenger is available as a standalone web client, which means that you don’t have to connect to Facebook to use the service.
Open your web browser, connect to Messenger and sign up with your Facebook credentials (email address/phone number) and password:
The web client gives you access to the following features: send text messages, make voice and video calls, delete or archive conversations, share content with your friends (documents, photos, GIFs, Emojis, Location…), and manage message requests.