Developed by devhub.io
An elegant messages UI library for iOS
Telegram web application, GPL v3
Conversations is an open source XMPP/Jabber client for the Android platform
Bring messenger.com to your OS X, Windows or Linux desktop.
Free and Open Source messaging and emailing app that combines common web applications into one.
Open-source XMPP client for Android
Simple user messaging package for Laravel (4 & 5)
Connect your App to Multiple Messaging Channels with the W3C Open standard.
OS X client for Facebook Messenger
Definitely the best Ruby client for Bots on Messenger
Allows user to take full control of the terminal of their computer through Facebook's messaging service.