REST vs GraphQL vs WebSockets: Understanding the Differences

When building modern applications, especially those that need to exchange data between clients and servers, choosing the right communication method is crucial. Three common approaches are REST, GraphQL, and WebSockets. While they all enable data exchange, they work very differently and are suited for different scenarios.

1. REST (REpresentational State Transfer)

REST is the most traditional and widely used method for building APIs. It uses standard HTTP methods like GET, POST, PUT, and DELETE to interact with resources. Each resource has its own endpoint (e.g., /users, /products/123).

How it works:

• The client sends a request to a specific endpoint.
• The server responds with a predefined data structure.
• Each request is independent, meaning no persistent connection is kept.

Example:
GET request (fetching data)

// Get user details
fetch('https://api.example.com/users/42')
  .then(response => response.json())
  .then(data => {
    console.log('User details:', data);
  })
  .catch(error => console.error('Error:', error));

POST request (creating new data)

// Create a new user
fetch('https://api.example.com/users', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    name: 'Alice',
    email: '[e-mail]'
  })
})
  .then(response => response.json())
  .then(data => {
    console.log('New user created:', data);
  })
  .catch(error => console.error('Error:', error));

PUT request (updating existing data)

// Update user details
fetch('https://api.example.com/users/42', {
  method: 'PUT',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    email: '[e-mail]'
  })
})
  .then(response => response.json())
  .then(data => {
    console.log('User updated:', data);
  })
  .catch(error => console.error('Error:', error));

DELETE request (removing data)

// Delete a user
fetch('https://api.example.com/users/42', {
  method: 'DELETE'
})
  .then(response => {
    if (response.ok) {
      console.log('User deleted successfully');
    } else {
      console.error('Failed to delete user');
    }
  })
  .catch(error => console.error('Error:', error));

When to use REST:

• When data needs are simple and predictable.
• When you want a well-established, easy-to-implement approach.

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2. GraphQL (Graph Query Language)

GraphQL is a more flexible API query language. Instead of multiple endpoints, there’s typically one endpoint where the client specifies exactly what data it needs.

How it works:

• The client sends a query describing the required fields.
• The server responds with only that data—no more, no less.

Example:
Query to get a user’s name and email along with their last 3 orders:

POST https://api.example.com/graphql
Body:
{
  user(id: 42) {
    name
    email
    orders(limit: 3) {
      id
      total
    }
  }
}

Response:

{
  "data": {
    "user": {
      "name": "Alice",
      "email": "[e-mail]",
      "orders": [
        { "id": 101, "total": 250 },
        { "id": 102, "total": 180 },
        { "id": 103, "total": 90 }
      ]
    }
  }
}

When to use GraphQL:

• When different clients (web, mobile, IoT) need different sets of data.
• When performance and efficiency in data fetching matter.

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3. WebSockets

WebSockets create a persistent, two-way connection between the client and server, allowing instant updates without repeated requests.

How it works:

• Once the connection is established, both client and server can send messages anytime.
• This enables real-time updates, perfect for live features.

Example:
A chat app using WebSockets:

// Client connects
ws = new WebSocket("wss://chat.example.com")
ws.onmessage = (event) => console.log("New message:", event.data)

// Server sends updates instantly
Server -> Client: { "from": "Bob", "text": "Hello, Alice!" }

When to use WebSockets:

• When your application needs live updates (chat, dashboards, multiplayer games).
• When speed and continuous communication are essential.

Choosing the Right Approach

• Use REST when you need simplicity and well-structured, predictable endpoints.
• Use GraphQL when you want flexibility and efficiency in fetching data.
• Use WebSockets when you need real-time, continuous communication.

In some cases, applications even combine these technologies. For example, an app might use REST or GraphQL for fetching static data and WebSockets for live updates.