Build Your First REST API with Node.js and Express

What You'll Build

In this tutorial, you'll create a fully functional REST API using Node.js and Express. By the end, you'll have a working API that handles CRUD operations — Create, Read, Update, and Delete — for a simple resource like a to-do list.

Prerequisites

• Node.js (v18 or higher) installed on your machine
• Basic familiarity with JavaScript
• A terminal and a code editor (VS Code recommended)
• Postman or a similar API testing tool

Step 1: Initialize Your Project

Start by creating a new project directory and initializing it with npm:

mkdir my-api && cd my-api
npm init -y
npm install express

This creates a package.json and installs Express as a dependency.

Step 2: Create Your Entry Point

Create a file called index.js in your project root. This is where your server lives:

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

app.use(express.json());

app.get('/', (req, res) => {
  res.json({ message: 'Welcome to my API!' });
});

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

Step 3: Add CRUD Routes

Now let's add routes for a /tasks resource. We'll use an in-memory array to keep things simple:

let tasks = [];
let nextId = 1;

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

// POST a new task
app.post('/tasks', (req, res) => {
  const task = { id: nextId++, ...req.body };
  tasks.push(task);
  res.status(201).json(task);
});

// PUT update a task
app.put('/tasks/:id', (req, res) => {
  const index = tasks.findIndex(t => t.id === parseInt(req.params.id));
  if (index === -1) return res.status(404).json({ error: 'Not found' });
  tasks[index] = { ...tasks[index], ...req.body };
  res.json(tasks[index]);
});

// DELETE a task
app.delete('/tasks/:id', (req, res) => {
  tasks = tasks.filter(t => t.id !== parseInt(req.params.id));
  res.status(204).send();
});

Step 4: Test Your API

Run your server with node index.js, then use Postman or curl to test each endpoint:

• GET /tasks — retrieves all tasks
• POST /tasks — send a JSON body like {"title": "Learn Express"}
• PUT /tasks/1 — update task with ID 1
• DELETE /tasks/1 — delete task with ID 1

Next Steps

This is a great foundation. From here, you can:

1. Connect a real database like MongoDB or PostgreSQL
2. Add input validation with a library like Joi or Zod
3. Implement authentication using JWT
4. Add error-handling middleware for cleaner responses

REST APIs power the majority of modern web applications. Mastering Express gives you a versatile tool that scales from small projects to production-grade systems.