How to sign up for WhatsApp multi-device and log in to four devices at once

WhatsApp is one of the best messaging apps around, and it is finally getting multi-device login. The feature is now live for beta users on Android and iOS, and it lets you log in to four devices at the same time — and you don't have to stay connected to your phone to send messages. This is a big deal for the platform, and the feature is now being rolled out to beta users worldwide.