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.

HexChat

Open Source

HexChat is an open-source, cross-platform IRC client.

irssi

Open Source

Irssi is an IRC client program for Linux, FreeBSD, Mac OS X and Microsoft Windows.

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.

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…

qutIM

Open Source

qutIM is free and open-source multiprotocol (ICQ, Jabber, Mail.Ru, IRC, VKontakte) instant messenger.

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.

Bit Chat

Open Source

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

YakYak

Open Source

YakYak is a desktop chat client for Google Hangouts.

Tox

Open Source

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

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…

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.

Spark

Open Source

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

WeeChat

Open Source

WeeChat is a free and open-source Internet Relay Chat client, which is designed to be light and fast.

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 …