How to run Whatsapp without app?
Whatsapp web doesn't run standalone. It is an another frontend to an already installed and functioning Whatsapp session in a device. That is to say, if you have a device with Whatsapp already installed and connected to internet, then you can access it through Whatsapp Web as well (requires authentication from device). But the web functionality doesn't offer to create an account and use Whatsapp services so you're at loss here. 

More info: How do I use WhatsApp on my computer?