Open Source

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

Open Source

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

Imo

Free

Imo free video calls and chat is a kind of Communication apps for Android.

mIRC

Commercial

mIRC is an Internet Relay Chat (IRC) client for Windows.

Franz

Free

Franz is a free messaging app /former emperor of Austria, that combines chat & messaging services into one application.

Miranda NG

Open Source

Miranda NG is a successor of Miranda IM, a popular multi-protocol instant messaging client for Windows.

Instantbird

Open Source

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

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.

Tencent QQ

Free

Tencent QQ (QQ) is an instant messaging software service.

Coccinella

Open Source

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

Trillian

Freemium

Trillian is a proprietary multiprotocol instant messaging application.

Digsby

Open Source

Digsby provides you with IM, email and Social networks in one easy to use application.

Facebook Messenger

Free

Facebook Messenger is the official Facebook app that lets you have text conversations with all of your friends on the popular social network.

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…

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.

KakaoTalk

Freemium

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

Rambox

Open Source

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

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 …