gRPC vs REST: When Should You Use gRPC?

Should microservices communicate via REST or gRPC?

Core Differences

Protobuf: Size Is the Advantage

message User {
  int64 id = 1;
  string name = 2;
  string email = 3;
}

JSON rendering: {"id": 123, "name": "Zhang San", "email": "zhang@test.com"} → 58 bytes Protobuf encoding: → ~30 bytes, saving ~50%

In high-frequency call scenarios, the cumulative bandwidth difference is significant.

HTTP/2 Multiplexing

HTTP/1.1:  Connection 1 [req1 → res1] | Connection 2 [req2 → res2]  ← Head-of-line blocking
HTTP/2:    Single connection [req1,req2,req3] → [res2,res1,res3]  ← Multiplexing

When to Use gRPC

• ✅ High-frequency internal calls between microservices
• ✅ When streaming is needed (real-time push, large files)
• ✅ Polyglot environments (automatic code generation)
• ✅ Performance-sensitive scenarios

When to Use REST

• ✅ External APIs (browser compatibility)
• ✅ Simple CRUD
• ✅ When caching is needed (native HTTP cache support)
• ✅ Team unfamiliar with Protobuf

Use gRPC internally, REST externally—this is the current mainstream choice.

References:

• gRPC Official Documentation