Gajim Alternatives for Windows

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

Telegram is a free cloud-based instant messaging platform.

Trillian is a proprietary multiprotocol instant messaging application.

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

Psi is a free instant messaging application designed for the XMPP network (including Google Talk). Fast and lightweight, Psi is fully open-source and compatible with Windows, Linux, and Mac OS X.

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

Bitmessage is a decentralized, encrypted, peer-to-peer, trustless communications protocol that can be used by one person to send encrypted messages to another person, or to multiple subscribers.

Matrix is an open protocol for real-time communication. It is designed to allow users with accounts at one communications service provider to communicate with users of a different service provider via online chat, Voice over IP, and Videotelephony.

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

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.

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

Tkabber is a GPL instant messaging client for the XMPP protocol which uses the Tk toolkit for the GUI.