[seanp2k2]

JSON-RPC? Not in my 2017. The last time I've had to use that was with an old version of Zabbix https://www.zabbix.com/documentation/2.2/manual/api

Nah, it's all about http://jsonapi.org these days. GraphQL seems neat. Cap'n Proto also seems neat but I'm unaware of anything actually using it. gRPC is also neat but AFAIK not supported in a browser, so you need some kind of gateway to have it work with browser clients anyway (think SPAs calling APIs which can normally service server to server over gRPC). CPNP has the same-ish problem in that it doesn't fully work in browsers (serialization works but not RPC).