API design impacts system architecture. After building APIs with all three approaches, here’s how to choose.

REST APIs

Characteristics

  • Resource-based - URLs represent resources
  • HTTP methods - GET, POST, PUT, DELETE
  • Stateless - No server state
  • Standard - Widely understood

Example

GET    /api/users
GET    /api/users/123
POST   /api/users
PUT    /api/users/123
DELETE /api/users/123

GraphQL APIs

Characteristics

  • Single endpoint - One endpoint
  • Query language - Client-specified queries
  • Type system - Strong typing
  • Flexible - Client controls data

Example

query {
  user(id: "123") {
    name
    email
    posts {
      title
    }
  }
}

gRPC APIs

Characteristics

  • High performance - Binary protocol
  • Type safety - Protocol buffers
  • Streaming - Bidirectional streams
  • Efficient - Compact serialization

Example

service UserService {
  rpc GetUser(GetUserRequest) returns (User);
  rpc StreamUsers(StreamUsersRequest) returns (stream User);
}

When to Use Each

Use REST When:

  • Simple CRUD - Standard operations
  • Caching important - HTTP caching
  • File operations - Upload/download
  • Standard patterns - Well-understood

Use GraphQL When:

  • Complex queries - Multiple relationships
  • Mobile apps - Bandwidth optimization
  • Rapid iteration - Frontend changes
  • Multiple clients - Different needs

Use gRPC When:

  • High performance - Low latency critical
  • Internal services - Microservices
  • Streaming - Real-time data
  • Type safety - Strong contracts

Best Practices

  1. Choose appropriately - Based on needs
  2. Design carefully - Clear contracts
  3. Version APIs - Backward compatibility
  4. Document - Clear documentation
  5. Test - Comprehensive testing
  6. Monitor - Track usage
  7. Optimize - Performance tuning
  8. Evolve - Continuous improvement

Conclusion

API design choice depends on:

  • Use case - Requirements
  • Performance - Latency needs
  • Complexity - Query patterns
  • Team - Expertise

Use REST for simplicity, GraphQL for flexibility, gRPC for performance. The patterns shown here work for production APIs.

API design comparison from September 2023, covering REST, GraphQL, and gRPC.