Open Source

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

Open Source

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

Kopete

Open Source

Kopete is a multi-protocol, free software instant messaging client released as part of the KDE Software Compilation. Although it can run in numerous environme…

iMessage

Free

iMessage is an instant messaging service.

Spark

Open Source

Apache Spark is an open-source cluster-computing framework.

Psi+

Open Source

Psi is a cross-platform powerful XMPP/Jabber client (Qt, C++) designed for the Jabber power users. Psi+ is a development branch of Psi IM XMPP/Jabber client.

Kadu

Open Source

Kadu is a free and open source multi-platform instant messaging client that supports Gadu-Gadu, XMPP IM networks and other services based on XMPP like Google …

Tkabber

Open Source

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

Free

Telegram is a free cloud-based instant messaging platform.

Jitsi

Open Source

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

Instantbird

Open Source

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

Bitmessage

Open Source

Bitmessage is a decentralized, encrypted, peer-to-peer, trustless communications protocol that can be used by one person to send encrypted messages to another…