Open source Instant messaging for MAC OS X

HexChat

HexChat is an IRC client based on XChat, but unlike XChat it’s completely free for both Windows and Unix-like systems. (GPL)

Linux - Windows - MAC OS X

Instantbird

With Instantbird, we intend to redefine the way instant messaging is used, so that it works the way you want. Both simple and powerful, it will help you manage all your real time communications. (GPL)

Linux - Windows - MAC OS X

Jitsi

Jitsi (formerly SIP Communicator) is an audio/video and chat communicator that supports protocols such as SIP, XMPP/Jabber, AIM/ICQ, Windows Live, Yahoo! and many other useful features. (Apache)

Cross-platform

Spark

Spark is an Open Source, cross-platform IM client optimized for businesses and organizations. (GPL)

Linux - Windows - MAC OS X

4 applications