gRPC vs REST vs GraphQL — Pick the Right Protocol

REST = resource-based HTTP. gRPC = contract-first binary RPC. GraphQL = client-driven query API.

When to use

• REST: public APIs, browser clients, simple CRUD
• gRPC: internal service-to-service (performance, typed contracts, streaming)
• GraphQL: flexible client needs, multiple frontends needing different shapes

Tradeoffs

• gRPC requires protobuf tooling and isn't browser-native
• GraphQL N+1 query problem requires dataloaders; REST suffers over/under-fetching

Feature	REST	gRPC	GraphQL
Protocol	HTTP/1.1 or HTTP/2	HTTP/2	HTTP/1.1 or HTTP/2
Schema	OpenAPI (optional)	Protobuf (required)	SDL (required)
Browser support	Native	Requires grpc-web proxy	Native
Streaming	SSE / WebSocket	Bidirectional native	Subscriptions
Best for	Public APIs, CRUD	Internal services, performance	Flexible client queries

Go

// REST handler
func GetUserREST(w http.ResponseWriter, r *http.Request) {
    id := chi.URLParam(r, "id")
    user := userRepo.Find(id)
    json.NewEncoder(w).Encode(user)
}

// gRPC handler (proto: rpc GetUser(UserRequest) returns (UserResponse))
func (s *Server) GetUser(ctx context.Context, req *pb.UserRequest) (*pb.UserResponse, error) {
    user := s.repo.Find(req.Id)
    return &pb.UserResponse{Id: user.ID, Name: user.Name}, nil
}

// GraphQL resolver
func (r *Resolver) User(ctx context.Context, args struct{ ID string }) (*UserResolver, error) {
    user := r.repo.Find(args.ID)
    return &UserResolver{user}, nil
}

Python

# REST handler (Flask)
@app.get("/users/<user_id>")
def get_user_rest(user_id: str):
    user = user_repo.find(user_id)
    return jsonify(user)

# gRPC handler (proto: rpc GetUser(UserRequest) returns (UserResponse))
class UserService(pb2_grpc.UserServiceServicer):
    def GetUser(self, request, context):
        user = user_repo.find(request.id)
        return pb2.UserResponse(id=user.id, name=user.name)

# GraphQL resolver (Strawberry)
@strawberry.type
class Query:
    @strawberry.field
    def user(self, id: str) -> User:
        return user_repo.find(id)

Gotcha: gRPC streaming beats WebSockets for bidirectional service-to-service. But it's opaque to standard HTTP proxies and load balancers unless you configure L7 support.