Formerly called Gaim, Pidgin is an open source, a graphical multiheaded IM program for Linux, BSD, MacOS X and Windows multi-IM client that works similar to Trillian. Pidgin is compatible with many chat networks including; AIM, ICQ, Google Talk, Jabber/XMPP, MSN Messenger, Yahoo, Bonjour, Gadu-Gadu, IRC, Novell GroupWise Messenger, QQ, Lotus Sametime, SILC, SIMPLE, MySpaceIM, and Zephyr. It can support additional networks with the use of plug-ins.
Pidgin supports many features of these chat networks, such as file transfers, away messages, buddy icons, custom smilies, and typing notifications. Numerous plug-ins also extend Pidgin's functionality above and beyond the standard features.
Pidgin is free and contains no ads. The code is open source and licensed under the GNU General Public License.