Free

Telegram is a free cloud-based instant messaging platform.

Trillian

Freemium

Trillian is a proprietary multiprotocol instant messaging application.

Signal

Open Source

Signal is the most scalable encryption tool.

Wire

Free

Wire is a cross-platform, encrypted instant messaging client created by Wire Swiss. It is available for iOS, Android, Linux, Windows, macOS and Web browser cl…

ICQ

Free

ICQ is an open source instant messaging software.

qutIM

Open Source

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

Coccinella

Open Source

Coccinella is a free and open-source cross-platform client for the XMPP/Jabber-instant messaging-protocol.

Toky

Freemium

Toky is an automation platform.

Tox

Open Source

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

Viber

Freemium

Viber Free Messenger and Phone Calls.

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…

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…

Spark

Open Source

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

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.