WAdium is a free and open source instant messaging client for macOS that supports multiple IM networks, including Google Talk and XMPP. In the past, it has also supported AIM, ICQ, Windows Live Messenger and Yahoo! Messenger. Adium is written using macOS's Cocoa API, and it is released under the GNU GPL-2.0-or-later and many other licenses for components that are distributed with Adium.
WBitlBee is a cross-platform IRC instant messaging gateway, licensed under the terms of the GNU General Public License.
WCentericq is a text mode menu- and window-driven instant messaging interface that supports the ICQ, Yahoo!, AIM, MSN, IRC, XMPP, LiveJournal, and Gadu-Gadu protocols.
WEmpathy is an instant messaging (IM) and voice over IP (VoIP) client which supports text, voice, video, file transfers, and inter-application communication over various IM communication protocols.
WFire is an instant messaging client for Mac OS X, that can access IRC, XMPP, AIM, ICQ, Microsoft, Yahoo!, and Bonjour. All services are built on GPL’d libraries, including firetalk, libfaim, libicq2000, libmsn, XMPP, and libyahoo2. Fire supports OS X v10.1 and higher.
WKopete is a multi-protocol, free software instant messaging client released as part of the KDE Software Compilation. Although it can run in numerous environments, it was designed for and integrates with the KDE Plasma Workspaces. Kopete was started because ICQ blocked Licq from their network in 2001. According to the original author, Duncan Mac-Vicar Prett, the name comes from the Chilean Spanish word copete, meaning "a drink with your friends". Kopete has been nominated for multiple awards. The designated successor is KDE Telepathy from the KDE RTCC Initiative.
WMeebo was an instant messaging and social networking service provider. It was founded in September 2005 by Sandy Jen, Seth Sternberg, and Elaine Wherry, and was based in Mountain View, California. Initially the company offered a web-based instant messenger service, extending its offer in more general online chat and even social networking directions. In June 2012, Google acquired Meebo to merge the company's staff with the Google+ developers team.
WMiranda IM is an open-source multiprotocol instant messaging application, designed for Microsoft Windows. Miranda is free software distributed under the GNU GPL-2.0-or-later.
WPidgin is a free and open-source multi-platform instant messaging client, based on a library named libpurple that has support for many instant messaging protocols, allowing the user to simultaneously log in to various services from a single application, with a single interface for both popular and obsolete protocols, thus avoiding the hassle of having to deal with a new software for each device and protocol.
WMSN Messenger, later rebranded as Windows Live Messenger, was a cross-platform instant messaging client developed by Microsoft. It connected to the Microsoft Messenger service while also having compatibility with Yahoo! Messenger and Facebook Messenger. The client was first released as MSN Messenger Service on July 22, 1999, and was marketed under the MSN branding until 2005 when it was rebranded under Windows Live. It has since been officially known by its second name, although its first name was still used colloquially by most of its users. In June 2009, Microsoft reported the service attracted over 330 million active users each month, placing Messenger among the most widely used instant messaging clients in the world.
WYahoo! Messenger was an advertisement-supported instant messaging client and associated protocol provided by Yahoo!. Yahoo! Messenger was provided free of charge and could be downloaded and used with a generic "Yahoo ID" which also allowed access to other Yahoo! services, such as Yahoo! Mail. The service also offered VoIP, file transfers, webcam hosting, a text messaging service, and chat rooms in various categories.