Overleaf

Collaborative LaTeX document editing

After absorbing its competition (ShareLatex), [overleaf](https://overleaf.com) is the only service of its kind that I know of. It is becoming very popular in academy, but offers limited service with a free account. They offer a Docker file to set up your own, but this is limited in management tools (almost none) and lacks some useful mechanisms (like the possibility of cloning the repo via git to work off-line).
An OS alternative would be much appreciated!