Hello, I built a tool which uses Whatsapp's qr authentication, you must try it. It's awesome :P

It's working the same way with Whatsapp Web, you should open your Whatsapp app and click Whatsapp Web and scan qr. And boom, you are in :)

ps: you should open this page with your computer

Since you can get complete access to someones WhatsApp account using this QR-Code, I would not recommend to try this.