I've been doing this for a while. My biggest hurdle was implementing sync between local and backend. I ended up using GitHub as my backend, Chrome extension as frontend, and implemented a simplified version of the Git client in SQLite with lots of triggers. Happy to share it with people. The app is here:
https://github.com/osmoscraft/tundra and the sync logic is here: https://github.com/osmoscraft/tundra/blob/master/apps/browse...