gRPC vs REST: Which API Style?
gRPC is a contract-first binary RPC over HTTP/2 with code generation; REST is resource-oriented JSON over HTTP that is ubiquitous and browser-friendly.
gRPC uses Protocol Buffers and HTTP/2 for compact, fast, strongly typed calls with streaming and generated clients, ideal for internal microservices. REST uses HTTP verbs and JSON, is universally supported, easy to debug with curl, and works natively in browsers. gRPC favors performance and typed contracts; REST favors reach, simplicity, and browser compatibility.
| gRPC | REST | |
|---|---|---|
| Payload | Protobuf (binary) | JSON (text) |
| Transport | HTTP/2 | HTTP/1.1+ |
| Contracts | Strong (.proto) | OpenAPI (optional) |
| Browser | Needs gRPC-Web | Native |
| Best for | Internal microservices | Public/browser APIs |
Use case and performance
gRPC excels for internal service-to-service calls needing low latency, streaming, and generated typed clients across languages. REST excels for public APIs, browser clients, and anything that benefits from human-readable payloads and broad tooling. Teams often expose REST externally and use gRPC internally.
In CI
gRPC pipelines run protoc/buf codegen and check generated code is up to date. REST pipelines validate OpenAPI and run contract tests. Both run on managed runners, where faster runners shorten codegen and contract-test steps.
The verdict
Internal, high-performance, strongly typed microservice calls: gRPC. Public, browser-facing, human-readable APIs with the broadest tooling: REST. A common architecture uses REST at the edge and gRPC between internal services.