How to Build a Simple REST API with Node.js and Express (2025 Guide)

Building a REST API is a key skill for developers in 2025. It doesn’t matter if you’re working on a web app, backend for mobile, or microservices – a well-designed API speeds up development and helps your project grow. This guide will show you how to create a basic REST API with Node.js and Express.js even if you’re just starting out.

🧰 Things You Need 

• Node.js on your computer (Get it here) 

• A grasp of JavaScript basics

• VS Code or another code editor 

• Postman or a similar tool to test APIs

📁 Step 1: Initialize Your Project

Open your terminal and run:

mkdir simple-rest-api
cd simple-rest-api
npm init -y

This creates a basic package.json file.

📦 Step 2: Install Express

• Install Express.js:
  
  npm install express

📄 Step 3: Create Your API Server

• Create a file called index.js and paste this code:

const express = require('express');
const app = express();
const PORT = 3000;

app.use(express.json());

let users = [
  { id: 1, name: 'Alice' },
  { id: 2, name: 'Bob' }
];

// GET all users
app.get('/users', (req, res) => {
  res.json(users);
});

// GET a single user
app.get('/users/:id', (req, res) => {
  const user = users.find(u => u.id === parseInt(req.params.id));
  user ? res.json(user) : res.status(404).send('User not found');
});

// POST a new user
app.post('/users', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

// DELETE a user
app.delete('/users/:id', (req, res) => {
  users = users.filter(u => u.id !== parseInt(req.params.id));
  res.send('User deleted');
});

app.listen(PORT, () => console.log(`Server running on http://localhost:${PORT}`));

🧪 Step 4: Test Your API

Use Postman or Hoppscotch to test these endpoints:

• DELETE /users/:id – Delete a user

• GET /users – List all users

• GET /users/:id – Get user by ID

• POST /users – Add new user (JSON body: { "name": "John" })

🔐 Step 5: Add CORS (Optional)

To allow cross-origin requests, install and enable CORS:

npm install cors

Then add to your code:

const cors = require('cors');
app.use(cors());

Congratulations! You have just developed your first working REST API using Node.js and Express. It is a basic version, but it is a scalable structure – you can add middleware, authentication, and a database! Please check back for our next guide on connecting to MongoDB.More Posts on Flymingotech.in