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Jatin Gupta
Jatin Gupta

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Why Companies Like Google Prefer gRPC for Microservices

#microservices #architecture #webdev #backend

REST vs gRPC
REST changed how applications communicate over the internet. But when companies started building hundreds of microservices that needed to talk to each other millions of times per second, REST began to show its limitations. That's where gRPC came in.

REST vs gRPC architecture overview

Introduction
If you've built APIs before, you've probably used REST.
A client sends an HTTP request, the server responds with JSON, and everything works perfectly.

But what happens when:

  • Thousands of services communicate internally?
  • Low latency becomes critical?
  • Network traffic becomes massive?
  • Multiple programming languages are involved? This is exactly the challenge Google faced while running its enormous distributed systems.

To solve this problem, Google developed gRPC (Google Remote Procedure Call) and open-sourced it in 2015.

Today, companies like Google, Netflix, Uber, Square, and many cloud-native applications use gRPC for internal service communication.

What is REST?

REST (Representational State Transfer) is an architectural style for designing APIs.
A REST API exposes resources through URLs.

Example:

GET /users/101
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Response:

{
  "id": 101,
  "name": "Jatin Gupta",
  "email": "jatin@example.com"
}
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REST commonly uses:

  • HTTP/1.1
  • JSON
  • URLs
  • GET, POST, PUT, DELETE methods

REST Workflow

Client
   |
HTTP Request
   |
Server
   |
JSON Response
   |
Client
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What is RPC?

RPC stands for Remote Procedure Call.
Instead of accessing resources, the client directly calls a function that exists on another machine.

Example:

user = getUser(101)
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Even though the function runs on a remote server, it feels like calling a local method.

What is gRPC?
gRPC is a modern implementation of RPC created by Google.
It allows services to communicate efficiently using:

  • HTTP/2
  • Protocol Buffers (Protobuf)
  • Code Generation
  • Bi-directional Streaming Instead of exchanging JSON, gRPC exchanges compact binary data.

gRPC Architecture

+-------------------+
|  Client Service   |
+-------------------+
          |
          |
          v
+-------------------+
|   gRPC Channel    |
+-------------------+
          |
          |
          v
+-------------------+
|   Server Service  |
+-------------------+
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The client calls a method directly:

userService.getUser(101)
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The network communication happens automatically behind the scenes.

How gRPC Works
Step 1: Define Service
Create a .proto file.

syntax = "proto3";

service UserService {
  rpc GetUser(UserRequest)
      returns (UserResponse);
}

message UserRequest {
  int32 id = 1;
}

message UserResponse {
  int32 id = 1;
  string name = 2;
}
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Step 2: Generate Code
gRPC generates:

  • Java classes
  • Go classes
  • Python classes
  • Node.js classes
  • C# classes

Automatically.

Step 3: Implement Server

public UserResponse getUser(UserRequest request) {
    return UserResponse.newBuilder()
        .setId(1)
        .setName("Jatin")
        .build();
}
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Step 4: Call From Client

UserResponse user =
    client.getUser(request);
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No manual JSON parsing.
No URL creation.
No request serialization.

REST vs gRPC

| Feature         | REST      | gRPC             |
| --------------- | --------- | ---------------- |
| Protocol        | HTTP/1.1  | HTTP/2           |
| Data Format     | JSON      | Protocol Buffers |
| Speed           | Slower    | Faster           |
| Payload Size    | Large     | Small            |
| Streaming       | Limited   | Native           |
| Type Safety     | No        | Yes              |
| Code Generation | No        | Yes              |
| Browser Support | Excellent | Limited          |
| Microservices   | Good      | Excellent        |
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Why gRPC is Faster

  1. Binary Serialization REST uses JSON.

Example:

{
  "name":"Jatin"
}
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gRPC converts the same data into compact binary format.

Benefits:

  • Smaller payloads
  • Less bandwidth
  • Faster parsing

2. HTTP/2 Multiplexing
REST mostly uses HTTP/1.1.

Problem:
Multiple requests often require multiple connections.
gRPC uses HTTP/2.

Benefits:

  • Multiple requests on one connection
  • Reduced latency
  • Better throughput 
Single Connection
 ├── Request 1
 ├── Request 2
 ├── Request 3
 └── Request 4
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3. Strongly Typed Contracts
REST documentation can become outdated.

gRPC uses .proto files as the source of truth.

Benefits:

  • Clear contracts
  • Automatic validation
  • Better developer experience

Streaming: A Superpower of gRPC

REST follows:

Request -> Response
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gRPC supports:

1. Unary RPC

Request -> Response
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2. Server Streaming

Request -> Response 1
          Response 2
          Response 3
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3. Client Streaming

Request 1
Request 2
Request 3
        -> Response
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4. Bidirectional Streaming

Client <----> Server
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Both can send messages simultaneously.
This is extremely useful for:

  • Live chats
  • Gaming
  • Video streaming
  • IoT devices
  • Real-time analytics

Why Google Uses gRPC
Google runs one of the world's largest distributed systems.
A single user action may trigger dozens of services.

Example:

Search Service
      |
      +--> Ranking Service
      |
      +--> Ad Service
      |
      +--> User Profile Service
      |
      +--> Analytics Service
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If every communication used JSON:

  • More bandwidth
  • More CPU usage
  • More latency

gRPC solves these issues by providing:

✅ Smaller messages

✅ Faster communication

✅ Automatic code generation

✅ Better scalability

✅ Streaming support

Does gRPC Replace REST Completely?

  • No. This is one of the biggest misconceptions.

REST is still the best choice for:

  • Public APIs
  • Browser applications
  • Third-party integrations
  • Mobile app backends
  • Simpler systems Example: 
Frontend App
      |
     REST
      |
API Gateway
      |
     gRPC
      |
Microservices
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This hybrid architecture is extremely common today.

When Should You Use REST?
Choose REST when:

  • Building public APIs
  • Working with browsers
  • Simplicity matters
  • Human-readable responses are needed
  • Third-party developers consume your API

When Should You Use gRPC?

Choose gRPC when:

  • Building microservices
  • Performance matters
  • Low latency is critical
  • High traffic systems exist
  • Streaming is required
  • Multiple programming languages are involved

Real-World Example
Imagine an e-commerce platform.

REST Architecture

Frontend
   |
 REST
   |
Backend
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Works perfectly.

Microservice Architecture

Frontend
    |
 REST API Gateway
    |
 --------------------------------
 |        |        |            |
User    Order   Payment   Inventory
         gRPC Services
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Now hundreds of service-to-service calls happen every second.
gRPC becomes the better option.

Conclusion

REST revolutionized web APIs and remains the standard for public-facing services. However, as applications evolved into large-scale distributed systems, the need for faster and more efficient communication became critical.

That's why Google created gRPC.
The real question isn't "REST or gRPC?"

It's:

"Where should I use REST, and where should I use gRPC?"

The most successful modern systems combine both:

  • REST for external communication.
  • gRPC for internal microservice communication. And that's why gRPC has become the backbone of many high-performance cloud-native applications today.

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