How to Build REST API with Node.js and Express

Learn how to build your first REST API using Node.js and Express, including routes, JSON responses, HTTP methods, and status codes.

Building Your First REST API with Node.js and Express

Learning Node.js is exciting, but eventually every developer asks:

How do I build an actual backend application?

The answer starts with a REST API .

REST APIs power:

• Mobile applications
• Web applications
• Dashboards
• SaaS products
• AI applications
• E-commerce platforms

In this guide, you'll build your first REST API using Node.js and Express.

What Is a REST API?

A REST API allows applications to communicate using HTTP requests.

For example:

These four methods form the foundation of most backend applications.

Step 1: Create a Project

Initialize a new project:

  mkdir first-api
cd first-api
npm init -y
  

Step 2: Install Express

  npm install express
  

Step 3: Create server.js

  const express = require("express");

const app = express();

const PORT = 5000;

app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});
  

Run:

  node server.js
  

Output:

  Server running on port 5000
  

Step 4: Create Your First Route

  app.get("/", (req, res) => {
  res.send("Hello API");
});
  

Visit:

  http://localhost:5000
  

Response:

  Hello API
  

Congratulations.

You just created your first API endpoint.

Step 5: Return JSON

Modern APIs usually return JSON.

  app.get("/api/users", (req, res) => {
  res.json([
    {
      id: 1,
      name: "Sachin"
    },
    {
      id: 2,
      name: "Developer"
    }
  ]);
});
  

Output:

  [
  {
    "id": 1,
    "name": "Sachin"
  },
  {
    "id": 2,
    "name": "Developer"
  }
]
  

Step 6: Handle POST Requests

Enable JSON parsing:

  app.use(express.json());
  

Create a POST route:

  app.post("/api/users", (req, res) => {
  const user = req.body;

  res.status(201).json({
    message: "User created",
    user
  });
});
  

Step 7: Test Using Postman

Send:

  POST /api/users
  

Body:

  {
  "name": "John"
}
  

Response:

  {
  "message": "User created",
  "user": {
    "name": "John"
  }
}
  

Common REST Status Codes

Why REST APIs Matter

REST APIs are the communication layer of modern applications.

Frontend applications, mobile apps, and external services all rely on them.

Best Practices

• Use meaningful routes.
• Return proper status codes.
• Validate input data.
• Keep responses consistent.
• Handle errors properly.

Conclusion

Building a REST API is the first major milestone in backend development.

From here, you'll start learning how professional backend systems are designed and scaled.