Building REST APIs with Node.js: A Complete Beginner's Guide

Why Node.js for APIs?

Node.js is one of the most popular choices for building APIs, and for good reason:

• JavaScript everywhere — same language on frontend and backend
• Non-blocking I/O — handles thousands of concurrent connections efficiently
• Massive ecosystem — npm has packages for virtually everything
• Fast development — get from idea to working API in minutes

Setting Up Your First API

Start with Express, the most popular Node.js web framework:

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

Create server.js:

javascript
const express = require('express');
const app = express();

app.use(express.json());

// In-memory data store
let todos = [
  { id: 1, title: 'Learn Node.js', completed: false },
  { id: 2, title: 'Build an API', completed: false },
];

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

// GET single todo
app.get('/api/todos/:id', (req, res) => {
  const todo = todos.find(t => t.id === parseInt(req.params.id));
  if (!todo) return res.status(404).json({ error: 'Not found' });
  res.json(todo);
});

// POST new todo
app.post('/api/todos', (req, res) => {
  const todo = {
    id: todos.length + 1,
    title: req.body.title,
    completed: false,
  };
  todos.push(todo);
  res.status(201).json(todo);
});

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

app.listen(3000, () => console.log('API running on port 3000'));

REST API Best Practices

Use Proper HTTP Methods

• GET — Read data (never modify)
• POST — Create new resources
• PUT/PATCH — Update existing resources
• DELETE — Remove resources

Use Meaningful Status Codes

• 200 — Success
• 201 — Created
• 204 — No Content (successful delete)
• 400 — Bad Request (client error)
• 404 — Not Found
• 500 — Server Error

Add Error Handling

javascript
// Global error handler
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({
    error: 'Something went wrong',
    message: process.env.NODE_ENV === 'development' ? err.message : undefined,
  });
});

Validate Input

Never trust client data. Use a validation library like zod or joi:

javascript
const { z } = require('zod');

const todoSchema = z.object({
  title: z.string().min(1).max(200),
  completed: z.boolean().optional(),
});

Beyond the Basics

Once you have the fundamentals, explore:

• Database integration — PostgreSQL, MongoDB, or Prisma ORM
• Authentication — JWT tokens, OAuth, or session-based auth
• Rate limiting — Protect your API from abuse
• API documentation — OpenAPI/Swagger for auto-generated docs
• Testing — Unit tests with Jest, integration tests with Supertest

Hands-On Practice

Theory only gets you so far. Our Node.js REST APIs course lets you build real APIs in interactive lab environments — no local setup needed.