Nope, locally. Roughly I'm doing something like that https://gist.github.com/vladmiller/0be83755e65cf5bd942ffba22...

Example is a bit bad, but roughly shows how we're using. I have built a custom sync API that accepts in the body a list of <object_id>:<short_hash> and returns a kind of json-list in a format

<id>:<hash>:<json_object>\n <id>:<hash>:<json_object>\n

API compares what client knows vs. current state and only returns the objects that were updated/created and separately objects that were removed. Not ideal for large collections (but then again why did I store 50mb of historical data on the client in the first place? :D)