A GTK+ based multi-protocol instant messaging client

Pidgin is a chat program that allows you to log into accounts on multiple
chat networks simultaneously. It runs on Windows, Linux, and other
UNIX-like operating systems.
Supports many protocols including XMPP/Jabber, IRC, Bonjour and others
via plugins. Features tabbed conversations, file transfer, buddy pounces,
away messages, and an extensive plugin system.