Universal RPC framework released as open source by Google on GitHub in 2015. Built on two pillars: HTTP/2 (multiplexed streaming, data compression) and Protocol Buffers (binary serialization/deserialization). Made for high performance, strong typing guarantees, data streaming, and security by design. Powers many public Google APIs and is used by AnyCable to connect the external WebSocket server to the Rails application. Trade-offs vs REST: much faster (streaming + binary encoding) but harder to integrate because client and server must share a protofile contract that has to be updated on both sides whenever it changes, and harder to debug because the wire format is not human-readable. In Emiliano's wroclove.rb 2026 talk he defines an OrderService protofile with a CreateOrder RPC, generates Ruby classes via Google's tooling, runs the gRPC server on port 50051, and drives it with grpcurl; he has used gRPC in production for a snowplow fleet-tracking application that needs to scale to ~10,000 vehicles the moment snow starts falling.