Pidgin

Open Source

Pidgin is a free and open-source chat client which supports AIM, Google Talk, ICQ, XMPP protocols.

Trillian

Freemium

Trillian is a proprietary multiprotocol instant messaging application.

Miranda IM

Open Source

Miranda IM is an open source multiprotocol instant messaging application, designed for Microsoft Windows.

IM+

Freemium

IM+ supports simultaneously major IM services, including Google Talk, Twitter DMs, Yahoo!, AIM/iChat, ICQ, Jabber (and Slack through Jabber), etc.

Gajim

Open Source

Gajim is an instant messaging client for the XMPP protocol which uses the GTK+ toolkit.

KakaoTalk

Freemium

KakaoTalk (Korean: 카카오톡), or sometimes KaTalk, is a free mobile instant messaging application for smartphones with free text and free call features.

Tkabber

Open Source

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

Adium

Open Source

Adium is an Open source multi-protocol instant messaging client for Mac OS X, supports MSN, Jabber, Yahoo! and other networks.

Jitsi

Open Source

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

Empathy

Open Source

Empathy is an instant messaging (IM) and voice over IP (VoIP) client which supports text, voice, video, file transfers, and inter-application communication ov…

Psi

Open Source

Psi is a free instant messaging application designed for the XMPP network (including Google Talk). Fast and lightweight, Psi is fully open-source and compatib…