Gobby is a Free Software licensed under GNU GPLv2. We have used Gobby for Editing Collaboratively for discussions and draft preparation. It has features such as Chat among the participants. It can also be used as a normal text editor. It is working fine except that it has some issue with Ubuntu iBus. We have tried it from the same network and from remote locations to use it. It can be effectively used in collaborative meetings to take the minutes, parallel analysis of source code, edit documents without storing it in a server parallelly.
Gobby - https://gobby.github.io/
Wiki - https://github.com/gobby/gobby/wiki