JamBox is a community project that uses Perforce solutions to support collaboration for Game Jams.
It is essentially a Perforce server and a customized version of Swarm.
There is a free 20 user license with the 2015.2 release of Perforce.
Check the Perforce licensing page for the most up to date information.
Feel free to log issues and feature requests here.
We're on Slack. Email firstname.lastname@example.org with 'Add me' in the subject for an invite.
Commit history here.