Might be interested in PouchDB/CouchDB which can be offline and resync relatively easily. Slightly different approach than other SQL based RDBMS though. In th

Might be interested in PouchDB/CouchDB which can be offline and resync relatively easily. Slightly different approach than other SQL based RDBMS though. In the end, it gets complicated to support offline web-apps and really depends on your usage. I had to work on a water dispensing system over a decade ago that needed to be able to work "offline" at a given site... I used firebird embedded locally, and a remotely available server for syncing against. All accounts and balances were synced to each site, so that they could operate in offline for dispensing water to carrier trucks. There were rules on offline term (up to a week) and balance carry to reduce the risk of a negative balance. In the end it worked well, but it wasn't at all simple. Active/Inactive and syncing transactions was at least interesting, and that was for a relatively simple data model. More complex models would be, of course, more complicated... and almost exponentially so.