qTox - A Qt graphical user interface for Tox.
Empathy - Apps/Empathy - GNOME Wiki!
Tox - Send messages, files, create groups and make Tox to Tox audio and video calls. Securely.
Gajim - Full featured and easy to use Jabber client
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
IM+ - Chat everywhere! IM+ is the most widely used mobile IM app! Connect all-in-one to MSN, Yahoo!, Goo...