In this tutorial, we will create ssl enable websocket using ws module.


  • nodejs with npm
  • certbot to generate ssl certificate from letsencrypt

Step 1 — Generating SSL Certificate

Assuming you use ubuntu 16.04 the step are following

sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install certbot

If you’re using different system, please refer to this official documentation.

After certbot successfully installed, we can generate ssl certificate with command

sudo certbot certonly --webroot -w /var/www/html -d -d

Otherwise, if we don’t want to use webroot plugin we can use –standalone flag to generate ssl certificate.

Please make sure that port 443 is not being used when generating ssl certificate using standalone mode. We can temporarily stopping webserver/other process for using port 443 and start again webserver when we done.

sudo certbot certonly --standalone -d -d

This command will generate a single certificate for domain and Now we can copy certificate file located in (usually) /etc/letsencrypt/live/

Step 2 — Create WebSocket Server Project

For now, lets create a project name secure-websocket in our home directory and initiating nodejs project.

mkdir secure-websocket
cd secure-websocket
npm init
# Fill all the necessary information
npm install ws --save
npm install fs --save
npm install https --save

All dependencies is ready, now we need to copy our ssl certificate so the application can access it without superuser privileges.

# create directory to contain ssl certificate
mkdir ssl-cert

# copy ssl certificate to our project directory
sudo cp /etc/letsencrypt/live/ ssl-celt/fullchain.pem
sudo cp /etc/letsencrypt/live/ ssl-celt/privkey.pem

After ssl certificate is ready we can write our application code. Create a new file named index.js and copy this code.

// Minimal amount of secure websocket server
var fs = require('fs');

// read ssl certificate
var privateKey = fs.readFileSync('ssl-cert/privkey.pem', 'utf8');
var certificate = fs.readFileSync('ssl-cert/fullchain.pem', 'utf8');

var credentials = { key: privateKey, cert: certificate };
var https = require('https');

//pass in your credentials to create an https server
var httpsServer = https.createServer(credentials);

var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({
    server: httpsServer

wss.on('connection', function connection(ws) {
    ws.on('message', function incoming(message) {
        console.log('received: %s', message);
        ws.send('reply from server : ' + message)


To start websocket server run following command

nodejs index.js

We can test it with this chrome extension or other client to access wss://