Gobby
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.[3]
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 can 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.[4]
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).
Gobby also has realtime chat built-in.
Version 0.4.0 featured fully encrypted connections and further usability enhancements.[5]
Versions numbered 0.4.9x are preview releases for version 0.5.0. The most noticeable improvement is that it supports Undo,[6] using the adOPTed algorithm for concurrency control.[7]

