XMPP, originally called Jabber, is open protocol and many free and open-source software implementations have been distributed, in addition to freeware and commercial software.
Originally named Jabber, the protocol was developed by the eponymous open-source community in 1999 for near real-time instant messaging (IM), presence information, and contact list maintenance. Because XMPP is an open protocol, implementations can be developed using any software license and many server, client, and library implementations are distributed as free and open-source software. Numerous freeware and commercial software implementations also exist. 
