Trillian is a proprietary multiprotocol instant messaging application.

Miranda NG is a successor of Miranda IM, a popular multi-protocol instant messaging client for Windows.

Tkabber is a GPL instant messaging client for the XMPP protocol which uses the Tk toolkit for the GUI.

Jitsi (formerly SIP Communicator) is a free and open source multiplatform voice (VoIP), videoconferencing and instant messaging application.

Instantbird is a cross-platform instant messaging client based on Mozillas XULRunner and the open source library libpurple used in Pidgin.