WhatsApp by Facebook stock photo 6
Edgar Cervantes / Android Authority
TL;DR
  • WhatsApp is finally rolling out multi-beta support to beta testers.
  • The feature is available in the latest WhatsApp beta version for a limited number of users.
  • The company also detailed the inner workings of the feature, the changes to WhatsApp’s architecture required, and how it will function for users.

It’s nearly here. WhatsApp‘s long-awaited multi-device support has landed as an experimental feature. Facebook’s engineering team made the announcement this week while detailing the feature’s complex inner workings.

Per Facebook, multi-device support has prompted a “rethink” of the chat app’s architecture.

How multi-device support works

Previously, WhatsApp saw the primary smartphone as a “source of truth” — the device used as the cornerstone of that users’ account encryption. This forced this device to be available at all times, even when companion devices, like a PC connected to WhatsApp Web, were being used.

Now, Facebook has redesigned this system. WhatsApp’s new architecture ensures that companion devices can act independently while also maintaining synchronization with the primary smartphone where possible.

“WhatsApp multi-device uses a client-fanout approach, where the WhatsApp client sending the message encrypts and transmits it N number of times to N number of different devices — those in the sender and receiver’s device lists,” explains Facebook engineering team.

This design allows users to send messages or place calls from companion devices even if their primary smartphone is switched off or disconnected.

Through this arrangement, WhatsApp can also sync app data and message history across devices without relying on a central server. However, the company does store “a copy of each application state that all of someone’s devices can access” on a server for redundancy. The company notes that this data is “end-to-end encrypted with constantly changing keys known only to that person’s devices.”

What isn’t included

Annoyingly, users are allowed up to four companion devices on their account, but none can be smartphones. This makes the feature a lame duck for those who want to use a single WhatsApp account across two smartphones.

The beta also lacks key features. Initially, you won’t be able to view the live location of another user on companion devices, nor will you be able to call others from a companion device if they have a dated version of WhatsApp installed. Group invite handling is limited to the primary smartphone for now, too. There’s also limited functionality for Portal, WhatsApp Desktop, and WhatsApp Business users too.

How to activate WhatsApp multi-device beta

If you are already on WhatsApp’s beta channel, be sure to update your app. After this, you can check if the feature enrollment option is available on your device. To do this:

  • Open WhatsApp.
  • Tap the More options menu — the three-button menu in the top-right corner.
  • Tap Linked Devices.
  • Select Multi-device beta.
  • Tap Join beta.

The Multi-device beta option will only be visible if the feature is available to you. Although I receive WhatsApp beta builds, the feature was not available on my device.

If you want to leave the beta, you can do that too. Follow the same steps above, but tap Leave beta at the final step instead.

WhatsApp hasn’t announced when multi-device support is due to hit stable builds. We imagine the company still has several bugs to squash and functionality to polish. Nevertheless, after months of rumors and teasers, the beta rollout is the first sense that multi-device support is nearly ready for primetime.