[fanpu]

Overleaf (https://overleaf.com/) is pretty popular for this, and also tracks things like edit history

[xigoi]

Unfortunately, it doesn't allow you to bring your own editor, so I have to put up with its half-assed implementation of Vim.

[grumdan]

It doesn't work super well during live collaboration, but Overleaf does allow git access to the underlying document: https://www.overleaf.com/learn/how-to/Using_Git_and_GitHub