Ignite Realtime Spark IM Client

https://www.igniterealtime.org/projects/spark/

Ignite Realtime Spark is an open-source, cross-platform instant messaging (IM) client designed for businesses and organizations, optimized for real-time collaboration using the XMPP protocol. It is heavily integrated with the Openfire server and offers secure, tabbed conversations, file transfers, and telephony integration, serving as a secure alternative to public IM networks.