&gt; I wonder how far along their implementation of the &#x27;off-line first&#x27; sync mechanism is, this is a non-trivial thing to implement.<p>The are using PouchDB + CouchDB for offline first &#x2F; syncing which is how I came to notice it (I am a maintainer for PouchDB). So their ability to sync should be reliable and well tested and if not then its bugs for us to fix :)