Direct app communication via bluetooth

I’m looking into the feasibility of connecting two devices such that they can send json back and forth. I assumed it would be simple with bluetooth but so far my search hasn’t turned up much other than a few people over the years asking similar questions with no responses. The native/cordova plugins I can find seem to be very specifically for arduino and not a general purpose thing…
But it’s 2018 now, surely we have this capability right?

I can set up a server to deliver the payloads back and forth, but that requires an internet connection (and the associated cost/maintenance of keeping it up). Not the end of the world, but ideally this should be usable anywhere with the need for a reliable internet connection.

Does anyone know how I can have apps communicate with each other over bluetooth?