It does not use CRDTs as they cannot be used to handle all the update requirements of this system.

It uses Paxos as the consensus algorithm, along with internal systems like the TrueTime API to enable us synchronously replicate across multiple data centers.

It would also be great to see a comparison to the couchDB-sync which I currently use via pouchdb/rxdb.

If this is similar to what powers GDocs, it's probably OT-based.