free, distributed and user-friendly IRC client with Twitter, and XMPP/Jabber support for Linux, Windows and macOS based on GNOME / GTK+

Smuxi 1.0 with persistent chat history, persistent message markers/counters, single application instance support and NickServ support. Packages are available for Windows, Mac OS X and Debian (Sid). Here you can read the full release announcement. For users running a development build of Smuxi it is recommended to simply upgrade to the newest development build.