gRPC

gRPC is a high-performance, open-source universal RPC (Remote Procedure Call) framework initially developed at Google in 2015 and now a Cloud Native Computing Foundation (CNCF) graduated project. It enables client and server applications to communicate transparently across machines, languages, and environments using Protocol Buffers (protobuf) as the default Interface Definition Language (IDL) and wire format. gRPC supports four service methods: unary RPC (client sends one request, server returns one response), server streaming RPC (client sends one request, server returns a stream of responses), client streaming RPC (client sends a stream of requests, server returns one response), and bidirectional streaming RPC (both sides send streams independently). Key advantages include: HTTP/2 as the transport protocol enabling multiplexing, header compression, and persistent connections (reducing latency by 30-50% over HTTP/1.1), Protocol Buffers binary serialization (3-10x smaller and 20-100x faster to parse than JSON), built-in load balancing, tracing, health checking, and retry logic via the gRPC Core and interceptors, pluggable authentication (TLS, OAuth2, JWT, custom), deadline propagation and cancellation, and code generation for 11 languages (C++, Java, Python, Go, Ruby, C#, Node.js, Android Java, Objective-C, PHP, Dart). The ecosystem includes gRPC-Web (browser support), gRPC-Gateway (REST/JSON proxy), Envoy (service mesh with native gRPC support), and Buf (protobuf management). Used at Google, Netflix, Square, Cisco, Docker, and Slack.