REST vs gRPC

Intermediate

Communication Patterns

REST uses HTTP/1.1 with JSON for simple, human-readable APIs. gRPC uses HTTP/2 with Protocol Buffers for high-performance, strongly-typed, streaming-capable inter-service communication.

Overview

REST (Representational State Transfer) is the dominant API style for web services. It uses standard HTTP methods (GET, POST, PUT, DELETE), JSON payloads, and URL-based resource identification. REST is simple, well-understood, browser-friendly, and works with any HTTP client. gRPC is a high-performance RPC framework from Google. It uses HTTP/2 for multiplexing and streaming, Protocol Buffers (protobuf) for compact binary serialisation, and code-generated client/server stubs for type safety. gRPC is 2-10x faster than REST for inter-service communication due to binary encoding, header compression, and connection multiplexing. However, it is not browser-native (needs grpc-web), harder to debug (binary), and requires schema management (.proto files). Use REST for public APIs and browser clients; use gRPC for internal microservice communication where performance matters.

REST — Resource-Oriented

REST models the world as resources (nouns) accessed via standard HTTP verbs. JSON is the standard format. It is simple, cacheable, and universally supported.

HTTP + JSON — REST API example

// REST API design
// Resource: /api/v1/orders
// Verbs: GET (read), POST (create), PUT (update), DELETE (remove)

// GET /api/v1/orders/123
// Response: 200 OK
{
  "id": "123",
  "userId": "u-42",
  "items": [{ "productId": "p-1", "qty": 2 }],
  "total": 99.99,
  "status": "SHIPPED"
}

// POST /api/v1/orders
// Request body: { "userId": "u-42", "items": [...] }
// Response: 201 Created

// Pros: simple, human-readable, browser-native, cacheable
// Cons: over-fetching (get all fields), N+1 API calls,
//       no streaming, text-based JSON is verbose

gRPC — High-Performance RPC

gRPC uses .proto files to define services and messages. Code generators produce type-safe client and server stubs. HTTP/2 enables multiplexing and bidirectional streaming.

Protobuf + Java — gRPC service definition

// order_service.proto — schema definition
syntax = "proto3";
package orders;

service OrderService {
  rpc GetOrder(GetOrderRequest) returns (Order);
  rpc CreateOrder(CreateOrderRequest) returns (Order);
  rpc StreamOrders(StreamRequest) returns (stream Order);  // server streaming
}

message Order {
  string id = 1;
  string user_id = 2;
  repeated OrderItem items = 3;
  double total = 4;
  string status = 5;
}

message GetOrderRequest { string id = 1; }

// Generated Java client usage
OrderServiceGrpc.OrderServiceBlockingStub stub =
    OrderServiceGrpc.newBlockingStub(channel);
Order order = stub.getOrder(
    GetOrderRequest.newBuilder().setId("123").build()
);

// Pros: 2-10x faster than REST, type-safe, streaming, code-gen
// Cons: not browser-native, binary (harder to debug), schema mgmt

When to Choose Which

Use REST for public/external APIs, browser clients, and simple CRUD. Use gRPC for internal microservice-to-microservice calls, real-time streaming, and polyglot environments where code generation helps.

Conceptual — REST vs gRPC decision matrix

// Decision matrix
//
// Factor              | REST          | gRPC
// ────────────────────────────────────────────
// Payload format      | JSON (text)   | Protobuf (binary)
// Protocol            | HTTP/1.1      | HTTP/2
// Performance         | Moderate      | 2-10x faster
// Streaming           | Limited (SSE) | Native (4 modes)
// Browser support     | ✅ Native     | ⚠️ grpc-web needed
// Human readability   | ✅ Easy       | ❌ Binary
// Type safety         | ❌ Manual     | ✅ Code-generated
// Caching             | ✅ HTTP cache | ❌ Not cacheable
// Tooling (Postman)   | ✅ Rich       | ⚠️ Limited
//
// Common pattern in production:
// External: REST (public API) or GraphQL (mobile/web)
// Internal: gRPC between microservices
// Gateway: REST→gRPC translation at API gateway

Key Points to Remember

1REST: HTTP/1.1 + JSON, simple, browser-friendly, cacheable — best for public APIs.
2gRPC: HTTP/2 + Protobuf, fast, type-safe, streaming — best for internal service-to-service calls.
3gRPC is 2-10x faster than REST due to binary encoding, HTTP/2 multiplexing, and header compression.
4gRPC supports 4 streaming modes: unary, server streaming, client streaming, bidirectional.
5Common pattern: REST for external APIs, gRPC for internal microservice communication.

Interview Questions

What are the key differences between REST and gRPC?

EasyTCS

Why is gRPC faster than REST?

MediumAmazon

When would you choose REST over gRPC for internal services?

MediumGoogle

How does gRPC handle streaming and why is it useful?

MediumFlipkart

Design the communication layer for a system with 50 microservices — which protocols and why?

HardNetflix

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