Update: They changed something, right now Firefox works natively, no need to spoof the user agent anymore

Old article left for reference

As you might know, WhatsApp Web works only on Google Chrome... or that what they want us to believe! I don't know if they put such a limitation after some "money incentive" from Google, or just because they don't have enough funds to do testing on Firefox (I can understand this, they were valued just 20 billion dollars).

The truth is that on Firefox it will work very well, this is how to enable it:

First of all, download UAControl.

Install it and restart Firefox. Then search "chrome user agent" on Google and click on the first result. Copy the user agent (which is a browser identifying string). Then go to UAControl and add Chrome user agent for the address "web.whatsapp.com"

Voilà! Magically, now WhatsApp Web works also on Firefox!

After pairing:

Notifications are working also:

What's weird is that if I go to see on my BlackBerry Z10, WhatsApp says that's connected to Firefox!!!