Pidgin (formerly named Gaim) is a free and open-source multi-platform instant messaging client, based on a library named libpurple that has support for many instant messaging protocols, allowing the user to simultaneously log into various services from one application.The number of Pidgin users was estimated to be over three million in 2007.Pidgin is widely used for its Off-the-Record Messaging (OTR) plugin, which offers end-to-end encryption.