WhatsApp is finally pushing an improvement to a key feature that even the Facebook-owned instant messaging service acknowledges has been a top request from users for years.

On Wednesday, WhatsApp said it is rolling out a limited public beta test for its improved multidevice capability.

The update allows WhatsApp users for the first time to use the service on up to four nonphone devices without having the registered phone switched on or otherwise connected to the internet. According to a WhatsApp spokesperson, this chain of multiple devices can't have another phone in it.
"Each companion device will connect to your WhatsApp independently," said the messaging app in a post.

To be explicit, WhatsApp, which has over 2 billion users worldwide, has been supporting multidevice usage. A user can access the service, for example, through a web browser or a desktop application on their computer while they are simultaneously accessing it through their phone. The flow of multidevice support still requires the phone to have an internet connection.

According to WhatsApp:

Being compelled to run on a companion device is pretty slow and disconnects rather often — very frequently so, especially if the phone's connection is not very strong, its battery is almost dead, or if it kills the process through the OS. The single-operative companion device will not permit the user to, for instance, be in a call while checking their Portal messages.

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

In a whitepaper published today (PDF), WhatsApp has outlined how this feature works, which gives an insight into why it took so long to ship.

According to the company, the firm has developed new technologies to ensure that messages sync across multiple devices while maintaining end-to-end encryption, a rare feat in the market currently.

"To achieve this we had to rethink WhatsApp's architecture and design new systems which enabled the standalone multi-device experience, preserve privacy, and retain end-to-end encryption." "Each message is encrypted separately in the established pairwise session with every device. Once messages have been delivered they are deleted from the server," said the company.

The feature also doesn't alter how WhatsApp uses cloud backups for users, a spokesperson said. "The mechanism we use to synchronize messages and other app data across a user's devices is independent from our cloud backups," the spokesperson added, pointing to the whitepaper that describes the protocol in more detail.

WhatsApp did not provide a specific date for when it plans to roll this feature out to all its users. The firm, instead, said it is starting by rolling it out first to its existing beta users. Over the coming months, it intends to begin adding it as an opt-in beta feature for a small number of users on stable versions of the app, as well.

The option to join the beta will appear in your 'Linked devices' screen sometime in the near future!

Some of these features are in development with WhatsApp. It has an app exclusively designed for the iPad, along with the extension of last year's disappearing mode feature. This feature currently allows a user to set a seven-day timer on messages and intends to further expand it by allowing the user to share pictures and videos that can be viewed only once.