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

Introduction

Node.js combined with Express.js is one of the most popular stacks for building fast and scalable REST APIs. Express is a lightweight framework that simplifies routing, middleware, and request handling.

Step 1 — Verify Node.js Installation

Make sure Node.js and NPM are installed on your system:

node -v
npm -v

Step 2 — Create a New Project Folder

mkdir node-express-api

cd node-express-api

Step 3 — Initialize NPM Project

npm init -y

Step 4 — Install Express.js

npm install express

Step 5 — Create Entry File

Create a file named index.js:

touch index.js

Add the following code

const express = require("express");
const app = express();

app.use(express.json());

app.get("/", (req, res) => {
  res.json({ message: "API is running successfully" });
});

const PORT = 3000;
app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});

Step 6 — Start the Server

node index.js

Open your browser and visit:

http://localhost:3000

Step 7 — Create a Sample API Route

Add this route below the root route:

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

visit

http://localhost:3000/api/users

Step 8 — Install Nodemon (Optional)

npm install --save-dev nodemon

Update package.json:

"scripts": {
  "dev": "nodemon index.js"
}

Run server in development mode:

npm run dev

Useful Express Commands

| Command | Description | |-----------------------|---------------------------| | node index.js | Start server | | npm run dev | Start server with nodemon | | npm install express | Install Express |

Troubleshooting

If port 3000 is busy:

PORT=3001 node index.js

If nodemon is not recognized, install it globally:

npm install -g nodemon

Conclusion

Express.js makes it easy to build REST APIs with Node.js using clean and minimal code. This setup is ideal for backend services and full-stack applications.

Author

Marquefactory DevOps Team