Creating an HTTP Server

http.createServer

http.createServer(callback) returns a Server instance. The callback — called the request listener — is invoked once per incoming HTTP request. It receives two arguments:

req — an IncomingMessage object describing the request (method, URL, headers, body stream).
res — a ServerResponse object used to write the response.

Call server.listen(port, callback) to start accepting connections. The callback fires once the server is ready.

Status codes and headers

Every HTTP response has a status code and a set of headers. Use res.writeHead(statusCode, headersObject) to set both at once, before writing any body data.

Common status codes:

Code	Meaning
200	OK
201	Created
400	Bad Request
404	Not Found
500	Internal Server Error

res.end — sending the response body

res.end(data) writes the final chunk of the response body and signals to Node.js that the response is complete. Every request handler must call res.end() (or res.destroy()) — if you forget, the client will wait forever and the connection will time out.

You can also use res.write(data) to send data in chunks before calling res.end().

A complete server with status codes and headers

Node.js

const http = require('node:http');

const server = http.createServer(function(req, res) {
  // Set status code 200 and Content-Type header
  res.writeHead(200, {
    'Content-Type': 'text/html',
    'X-Powered-By': 'Node.js'
  });

  // Send the response body and close the connection
  res.end('<h1>Hello from Node.js!</h1><p>Status: 200 OK</p>');
});

server.listen(3000, function() {
  console.log('Server running at http://localhost:3000');
});

Needs the Node.js runtime — open in StackBlitz to run.

Open in StackBlitz, then visit http://localhost:3000 in the preview tab to see the rendered HTML response with correct headers.

Responding with different status codes

Node.js

const http = require('node:http');

const server = http.createServer(function(req, res) {
  if (req.url === '/') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('200 OK - Home page');
  } else if (req.url === '/created') {
    res.writeHead(201, { 'Content-Type': 'text/plain' });
    res.end('201 Created - Resource was created');
  } else {
    res.writeHead(404, { 'Content-Type': 'text/plain' });
    res.end('404 Not Found - No page at ' + req.url);
  }
});

server.listen(3000, function() {
  console.log('Server running at http://localhost:3000');
  console.log('Try: /, /created, /anything-else');
});

Needs the Node.js runtime — open in StackBlitz to run.