You can use whatever you want :). I personally would rather still go with Protobuf if I'm going to put in the effort to add a schema and codegen. It gives me o

You can use whatever you want :). I personally would rather still go with Protobuf if I'm going to put in the effort to add a schema and codegen. It gives me other nice-to-have features (faster [de]serialization, smaller messages, field numbers and schema evolution, nicer IDL [not JSON!], gRPC, ...) and does away with some problems intrinsic to JSON that no schema system will fix (terrible number type, lack of binary type, slow parsing). It also has some interop with JSON in the rare case you absolutely positively need to convert to/from it (which is IMO the only upside of using JSON Schema in case you need that interop).