Gajim
Gajim  is an instant messaging client for the XMPP protocol which uses the GTK toolkit. The name Gajim is a recursive acronym for Gajim's a jabber instant messenger. Gajim runs on Linux, BSD, macOS, and Microsoft Windows. Released under the GPL-3.0-only license, Gajim is free software. A 2009 round-up of similar software on Tom's Hardware found version 0.12.1 "the lightest and fastest jabber IM client".

Philosophy and features 

The goal of the Gajim project is to provide a full-featured and easy to use XMPP client for GTK users. Gajim uses PyGTK as GUI library, so it  does not require full GNOME to run, though it works nicely under a GNOME environment. Some of its features:
 Tabbed chat windows
 Group chat support (with MUC protocol)
 Emoticons, Avatars, File transfer, URL grabber, Bookmarks
 Systray icon, Speller
 TLS, OpenPGP and end-to-end encryption support (OpenPGP not available under Windows until version 0.15), including SSL legacy support
 Transport Registration support 
 Service Discovery including Nodes
 Wikipedia, dictionary and search engine lookup
 Multiple accounts support
 D-Bus Capabilities
 XML Console
 Jingle voice and video support (using the "python-farstream" library, no support in Windows yet)
 OMEMO
 HTTP file upload
Gajim is available in Basque, Bulgarian, Chinese, Croatian, Czech, English, Esperanto, French, German, Italian, Norwegian (Bokmål), Polish, Russian, Spanish, Slovak, Swedish, Ukrainian and others.

Third-party plugins
Gajim supports third-party plugins. Examples include:
 Gajim-OMEMO, adding support for OMEMO.

Security
Up until late 2011, it was possible to forge a link such that when a receiving Gajim user clicks on it, arbitrary code would be executed on the Gajim user's machine.

See also 

 Comparison of instant messaging clients

References

Reviews
 Joe 'Zonker' Brockmeier Review: Gajim Jabber client on Linux.com, September 16, 2005
 Mihai Marinof, Gajim Review. Free Jabber client for Linux. on Softpedia, 7 November 2006

External links

 
 Official wiki
 XMPP Software: Clients
 Unofficial XMPP/Jabber clients and OS usage statistics (5) by Lucas Nussbaum

Free instant messaging clients
Free XMPP clients
Instant messaging clients that use GTK
Software that uses PyGTK
Windows instant messaging clients
Free software programmed in Python
Applications using D-Bus