Building an HTTP server with Node.js http module

http.createServer Is the Foundation

The built-in http module lets you create an HTTP server without any framework. Understanding it makes Express and Fastify much less magical.

const http = require('http');

const server = http.createServer((req, res) => {
  const { method, url } = req;

  if (method === 'GET' && url === '/') {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({ message: 'Hello World' }));
    return;
  }

  if (method === 'GET' && url === '/health') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('OK');
    return;
  }

  res.writeHead(404, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({ error: 'Not found' }));
});

server.listen(3000, () => console.log('Running on :3000'));

Reading Request Body

let body = '';
req.on('data', chunk => { body += chunk.toString(); });
req.on('end', () => {
  const data = JSON.parse(body);
});

This raw approach works but is tedious. Express handles body parsing via middleware — this is why it exists.