Assuming the author of the article spots this on HN, I'd just like to say a quick thanks for mentioning Overleaf [1] in this! It's a nice easy to read article and it reminded me that we were planning to write one along these lines but never got around to it :)

It's interesting to see how CRDT has been adopted -- we wrote our own OT implementation for Overleaf (back when we were writeLaTeX) and it's still serving us well. We took a lot of inspiration from Etherpad [2], which is still a great collaborative editor, especially for notes.

We're now going over much of our code as we work on the integration with ShareLaTeX [3], which also has a very nice real time track changes / commenting implementation [4]. This helps with the UI aspect of collaboration, which is important on top of the use of OT or CRDT to ensure no version conflicts.

Good luck in your next projects, and I look forward to reading write ups like this of those too :)

[1] https://www.overleaf.com/

[2] http://etherpad.org/

[3] https://www.overleaf.com/blog/518-exciting-news-sharelatex-i...

[4] https://www.sharelatex.com/blog/2017/03/09/track-changes-and...

(Note: Edited for grammar)