Most of the comments here focus on Protobuf but the other half of gRPC is HTTP/2, and HTTP/2 is very complex. Good luck implementing a half-decent HTTP/2 clien

Most of the comments here focus on Protobuf but the other half of gRPC is HTTP/2, and HTTP/2 is very complex. Good luck implementing a half-decent HTTP/2 client or server library if your language doesn't support it already. This is easily a 6 months job. The other issue with HTTP/2 is that most client libraries require TLS to work. Development environments become harder to setup. It becomes harder to sniff the traffic during debugging. In client/server scenarios where both are on the same machine this also creates unnecessary overhead.