WhatsApp now available on 4 devices in Beta without a phone

WhatsApp head Will Cathcart announced the rollout of a limited public beta test for WhatsApp's updated multi-device capability. 

Currently, the Beta is available with a limited group of testers who are part of the WhatsApp's Beta programme, and will be rolled out globally soon. 

"With this new capability, you can now use WhatsApp on your phone and up to four other non-phone devices simultaneously -- even if your phone battery is dead," Cathcart said in a statement late on Wednesday. 

Each companion device will connect to your WhatsApp independently while maintaining the same level of privacy and security through end-to-end encryption that people who use WhatsApp have come to expect. 

"Importantly, we have developed new technologies to maintain end-to-end encryption while still managing to sync your data — such as contact names, chat archives, starred messages and more -- across devices," he informed. 

Until now, WhatsApp has only been available on one device at a time and desktop and web support only worked by mirroring off the phone with an active internet connection. 

The current WhatsApp experience for companion devices on web, macOS, Windows, and Portal uses a smartphone app as the primary device, making the phone the source of truth for all user data and the only device capable of end-to-end encrypting messages for another user, initiating calls, etc. 

"This architecture makes it easy to deliver a seamlessly synchronised experience between a phone and companion device without compromising on security," WhatsApp said. 

The company said that the new WhatsApp multi-device architecture removes all hurdles, no longer requiring a smartphone to be the source of truth while still keeping user data seamlessly and securely synchronised and private. 

Prior to the introduction of multi-device, everyone on WhatsApp was identified by a single identity key from which all encrypted communication keys were derived. 

With multi-device, each device now has its own identity key. 

"The WhatsApp server maintains a mapping between each person's account and all their device identities. When someone wants to send a message, they get their device list keys from the server," Cathcart informed. 

The company said it will also give people additional control and protections over which devices are linked to their account. 

First, everyone will continue to be required to link new companion devices by scanning a QR code from their phone. This process now requires biometric authentication before linking where people have enabled this feature on compatible devices. 

"Finally, people will be able to see all the companion devices linked to their account as well as when they were last used, and will be able to log out of them remotely if needed," WhatsApp said.