Pidgin

Open Source

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

Signal

Open Source

Signal is the most scalable encryption tool.

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…

ICQ

Free

ICQ is an open source instant messaging software.

Quassel IRC

Open Source

Quassel IRC, or Quassel, is a graphical, distributed, cross-platform IRC client.

Spark

Open Source

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

Rambox

Open Source

Rambox is a free and Open Source messaging and emailing app that combines common web applications into one.

Bit Chat

Open Source

Bit Chat is a secure, peer-to-peer, open source instant messenger with end-to-end encryption.

Zulip

Open Source

Zulip is a chat and collaborative software.

Tox

Open Source

Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption.

Jitsi

Open Source

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

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…

Gajim

Open Source

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

Instantbird

Open Source

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

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.

Finch

Open Source

Finch is a console-based IM program that lets you sign on to AIM, Jabber, MSN, Yahoo!, and other IM networks. It runs on Unixes. It uses GLib and ncurses.