gRPC vs REST — When to Use Which in Microservices

REST is the standard for web APIs. But for inter-service communication in microservices? gRPC offers better performance, type safety, and bi-directional streaming.

gRPC Advantages¶

• Protobuf — binary serialization, 5–10x smaller than JSON
• HTTP/2 — multiplexing, header compression, streaming
• Code generation — client and server from a .proto file
• Streaming — server-side, client-side, bidirectional

When REST, When gRPC¶

REST: public APIs, browser clients, simple CRUD, wide tooling support. gRPC: inter-service communication, high-throughput, streaming, polyglot environments (type-safe clients in any language).

Our Experience¶

We migrated the 5 highest-traffic inter-service connections to gRPC. Latency: -40%. Bandwidth: -60%. Code generation eliminates API mismatch bugs. REST stays for public APIs and frontend communication.

It’s Not “Either/Or”¶

gRPC for inter-service, REST for external. Both have their place.