gRPC

gRPC is a high-performance, open-source remote procedure call framework originally built at Google and now hosted by the Cloud Native Computing Foundation. It runs over HTTP/2 and uses Protocol Buffers as its interface definition language and binary message format, which lets services define strongly typed contracts and call each other with low latency across many programming languages.

• Protocol Buffers contract - Services and messages are defined in .proto files that generate client and server code in many languages.
• HTTP/2 transport - Multiplexing, header compression, and long-lived connections give gRPC its speed and support for streaming.
• Four call patterns - Unary, server-streaming, client-streaming, and bidirectional streaming cover a wide range of interaction styles.
• Built-in essentials - Deadlines, cancellation, and pluggable authentication are part of the framework rather than bolt-ons.

In real API operations gRPC is the protocol teams reach for when internal service-to-service traffic needs speed and strict contracts, sitting alongside REST and GraphQL rather than replacing them, which is why I keep pointing to a diverse API toolbox and multi-protocol governance instead of picking a single winner. Its binary, HTTP/2-only nature is also its known weakness at the edge, where browsers and simple consumers still expect plain HTTP, so providers often expose gRPC internally and a REST or gRPC-Web surface outward. As agent-to-agent communication grows, gRPC’s typed, streaming contracts make it a natural transport for machine-to-machine calls.