How to Set Up Your First REST API with Node.js and Express

APIs are the backbone of modern web applications.

Whether you’re building a single-page app, a mobile interface, or a microservice, a clean and scalable API structure is essential for maintainability and growth. In this article, we’ll walk through how to create a REST API using Node.js and Express, applying best practices in organization, routing, error handling, and modularization.

You’ll learn how to start from scratch and end up with a well-structured, production-ready API that can grow with your application. Once your API is ready, you can easily deploy it on a cloud platform like Galaxy, ensuring scalability and reliable performance.

This tutorial is ideal for beginners and intermediate developers looking to improve their backend skills.

Project Setup

Let’s initialize a new Node.js project and install the required dependencies:

mkdir node-api-galaxy

cd node-api-galaxy

npm init -y

npm install express dotenv

mkdir node-api-galaxy

cd node-api-galaxy

npm init -y

npm install express dotenv

Your file structure should look like this:

node-api-galaxy/

├── controllers/

├── routes/

├── .env

├── index.js

Creating the Express Server

Create the index.js file and add the basic setup:

const express = require('express');
require('dotenv').config();

const app = express();
app.use(express.json());

const PORT = process.env.PORT || 3000;

app.get('/', (req, res) => {
  res.send('API is running');
});

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

const express = require('express');
require('dotenv').config();

const app = express();
app.use(express.json());

const PORT = process.env.PORT || 3000;

app.get('/', (req, res) => {
  res.send('API is running');
});

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

Add a .env file with:

PORT=4000

PORT=4000

Organizing Routes and Controllers

Let’s create modular files for our routes and logic.

///routes/userRoutes.js
 
const express = require('express');
const router = express.Router();
const { getUsers, createUser } = require('../controllers/userController');

router.get('/', getUsers);
router.post('/', createUser);

module.exports = router;

///routes/userRoutes.js
 
const express = require('express');
const router = express.Router();
const { getUsers, createUser } = require('../controllers/userController');

router.get('/', getUsers);
router.post('/', createUser);

module.exports = router;

///controllers/userController.js

exports.getUsers = (req, res) => {
  res.status(200).json({ message: 'List of users' });
};

exports.createUser = (req, res) => {
  const user = req.body;
  res.status(201).json({ message: 'User created', data: user });
};

///controllers/userController.js

exports.getUsers = (req, res) => {
  res.status(200).json({ message: 'List of users' });
};

exports.createUser = (req, res) => {
  const user = req.body;
  res.status(201).json({ message: 'User created', data: user });
};

And import into index.js:

const userRoutes = require('./routes/userRoutes');

app.use('/api/users', userRoutes);

const userRoutes = require('./routes/userRoutes');

app.use('/api/users', userRoutes);

Now your API has the route /api/users with GET and POST functionality.

Middleware and Error Handling

Let’s create a basic error handler.

//middleware/errorMiddleware.js

function errorHandler(err, req, res, next) {
  console.error(err.stack);
  res.status(500).json({ error: 'Internal Server Error' });
}

module.exports = errorHandler;

//middleware/errorMiddleware.js

function errorHandler(err, req, res, next) {
  console.error(err.stack);
  res.status(500).json({ error: 'Internal Server Error' });
}

module.exports = errorHandler;

Then import it in index.js:

const errorHandler = require('./middleware/errorMiddleware');

app.use(errorHandler);

const errorHandler = require('./middleware/errorMiddleware');

app.use(errorHandler);

Best Practices Summary

• Use express.Router() for clean routing
• Keep controllers separate from routes
• Use .env for environment configuration
• Implement middleware for consistent error handling
• Keep code modular for scalability

Conclusion

In this article, you learned how to build and structure a REST API using Node.js and Express with best practices in mind. These techniques will help you scale your API, improve code maintainability, and prepare for real-world production deployments. Whether you plan to deploy on Galaxy or another cloud platform, this approach provides a solid backend foundation.