qTox - A Qt graphical user interface for Tox.
Psi-IM - Psi-IM is a messaging program that is designed for the XMPP network.
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
Toxic - Toxic is a client with an ncurses interface, written entirely in C.
Empathy - Apps/Empathy - GNOME Wiki!