Pidgin (software)
Pidgin (formerly named Gaim) is an open-source multi-platform instant messaging client, based on a library named libpurple. Libpurple has support for many commonly used instant messaging protocols, allowing the user to log into various services from one application.
The number of Pidgin users was estimated to be over 3 million in 2007.
Read more about Pidgin (software): Features, History, Criticisms, Other Notable Software Based On Libpurple