How to create an HTTPS server in Node.js?

The above answers are good but with Express and node this will work fine.

Since express create the app for you, I'll skip that here.

var express = require('express')
  , fs = require('fs')
  , routes = require('./routes');

var privateKey = fs.readFileSync('cert/key.pem').toString();
var certificate = fs.readFileSync('cert/certificate.pem').toString();  

// To enable HTTPS
var app = module.exports = express.createServer({key: privateKey, cert: certificate});

The Express API doc spells this out pretty clearly.

Additionally this answer gives the steps to create a self-signed certificate.

I have added some comments and a snippet from the Node.js HTTPS documentation:

var express = require('express');
var https = require('https');
var http = require('http');
var fs = require('fs');

// This line is from the Node.js HTTPS documentation.
var options = {
  key: fs.readFileSync('test/fixtures/keys/agent2-key.pem'),
  cert: fs.readFileSync('test/fixtures/keys/agent2-cert.cert')
};

// Create a service (the app object is just a callback).
var app = express();

// Create an HTTP service.
http.createServer(app).listen(80);
// Create an HTTPS service identical to the HTTP service.
https.createServer(options, app).listen(443);

Found this question while googling "node https" but the example in the accepted answer is very old - taken from the docs of the current (v0.10) version of node, it should look like this:

var https = require('https');
var fs = require('fs');

var options = {
  key: fs.readFileSync('test/fixtures/keys/agent2-key.pem'),
  cert: fs.readFileSync('test/fixtures/keys/agent2-cert.pem')
};

https.createServer(options, function (req, res) {
  res.writeHead(200);
  res.end("hello world\n");
}).listen(8000);

For Node 0.3.4 and above all the way up to the current LTS (v16 at the time of this edit), https://nodejs.org/api/https.html#httpscreateserveroptions-requestlistener has all the example code you need:

const https = require(`https`);
const fs = require(`fs`);

const options = {
  key: fs.readFileSync(`test/fixtures/keys/agent2-key.pem`),
  cert: fs.readFileSync(`test/fixtures/keys/agent2-cert.pem`)
};

https.createServer(options, (req, res) => {
  res.writeHead(200);
  res.end(`hello world\n`);
}).listen(8000);

Note that if want to use Let's Encrypt's certificates using the certbot tool, the private key is called privkey.pem and the certificate is called fullchain.pem:

const certDir = `/etc/letsencrypt/live`;
const domain = `YourDomainName`;
const options = {
  key: fs.readFileSync(`${certDir}/${domain}/privkey.pem`),
  cert: fs.readFileSync(`${certDir}/${domain}/fullchain.pem`)
};