AFAIK this is how Felica works which is the system for many of the transit systems across the world as well as a payment system built into feature phone since 2

AFAIK this is how Felica works which is the system for many of the transit systems across the world as well as a payment system built into feature phone since 2005, Android since 5-6 years ago and iPhone since iPhone7 in Japan and 8 everywhere else. https://en.wikipedia.org/wiki/FeliCa https://en.wikipedia.org/wiki/FeliCa I don't know for a fact that it works without a DB but I do know that they exist in places that don't seem to access to a DB and they work instantly (no long pause like credit cards).