Gajim is an XMPP client written in PyGTK. The goal of Gajim's developers is to provide a full featured and easy to use xmpp client for the GTK+ users. Gajim does not require GNOME to run, eventhough

Psi is a free instant messaging application designed for the XMPP network. Fast and lightweight, Psi is fully open-source and compatible with Windows, Linux, and macOS.