Pidgin

Pidgin is an easy to use, multi-protocol chat client client used by millions. Connect to AIM, MSN, Yahoo, XMPP, and more chat networks all at once. It has built-in...

Free Open Source Mac Windows Linux BSD PortableApps.com ... Xfce

Psi

An instant messaging application for Windows, Linux, and Mac OS X that connects to the free, open XMPP network. Localized versions of Psi are available in almost...

Free Open Source Mac Windows Linux BSD

Messenger for Desktop

A simple & beautiful app for Facebook Messenger. Chat without distractions on any Operating System.

• Bundleware
  Be careful during the installation: https://alternativeto.net/discussions/applications/11718/be-careful-in-the-installation/

Free Open Source Mac Windows Linux

Spark

Spark is an Open Source, cross-platform IM client optimized for businesses and organizations. It features built-in support for group chat, telephony integration, and...

Free Open Source Mac Windows Linux Self-Hosted

Sim-IM

Sim-IM, Simple Instant Messenger, is a multiple protocol instant messenger for MS Windows, GNU/Linux, FreeBSD. Sim-IM supports Jabber/XMPP, Google Talk, ICQ and AIM...

• Discontinued
  The project is no longer developed. Last versions for Windows and Linux date back to 2008, but they can be still downloaded from the official website.

Free Windows Linux BSD

Galaxium

Galaxium is an instant messenger application designed for the GNOME desktop. It will allow you to connect to MSN, Jabber, and IRC. You can communicate with your family...

Free Linux

Centericq

Centericq is a text mode menu- and window-driven IM interface that supports the ICQ2000, Yahoo!, AIM, IRC, MSN, Gadu-Gadu and Jabber protocols.

• Discontinued
  The program is no longer updated. Last version, 4.21.0, released in September 2005, can be still downloaded from the official website.

Free Open Source Mac Windows Linux BSD