Openfire is an open source real-time collaboration system (it's a chat server, supporting Jabber/XMPP and other protocols, but it also does much more than that), licensed under the GPL. If you've been thinking about setting up your own real-time collaboration server, whether on an intranet or as a component of your public-facing web presence, you may want to try my Openfire on Debian Linux tutorial. I wrote it with beginners in mind; it walks you through the base system preparation and application installation step by step. I hope the community finds this useful, and look forward to feedback on the tutorial .