Mixer is a Blender addon for real time collaboration in Blender. It allows multiple Blender users to work on the same scene at the same time and is developed by the R&D department of Ubisoft Animation Studio (former partner).
Mixer synchronizes in real time the modifications done to the scene and the objects it contains. During a collaboration session, Mixer displays the position of other participants and highlights their selections.
A series of videos presenting Mixer features is available on YouTube here and the software is available here GitHub.