Gobby is a free software collaborative real-time editor available on Windows and Unix-like platforms. (It runs on Mac OS X using Apple’s X11.app). It was initially released in June 2005 by the 0x539 dev group.
It features a client-server architecture which supports multiple documents in one session, document synchronisation on request, password protection and an IRC-like chat for communication. Users could choose a colour to highlight the text they have written in a document. Gobby is fully Unicode-aware, provides syntax highlighting for most programming languages and has basic Zeroconf support.
A dedicated server called Sobby is also provided, together with a script which could format saved sessions for the web (e.g. to provide logs of meetings with a collaboratively prepared transcript).
Version 0.4.0 featured fully encrypted connections and further usability enhancements.