However, it comes with some significant reliability trade-offs: By requiring the phone to perform all operations, companion devices are slower and frequently get disconnected - especially when the phone has a poor connection, its battery is running low, or the application process gets killed by the phone’s OS. This architecture makes it easy to deliver a seamlessly synchronized experience between a phone and companion device without compromising on security. Companion devices maintain a persistent secure connection with the phone and simply mirror its contents on their own UI. 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. To achieve this, we had to rethink WhatsApp’s architecture and design new systems to enable a standalone multi-device experience while preserving privacy and end-to-end encryption. 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. 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. With this new capability, you can now use WhatsApp on your phone and up to four other nonphone devices simultaneously - even if your phone battery is dead.

Today, we’re announcing the rollout of a limited public beta test for WhatsApp’s updated multi-device capability. For years, people have been asking us to create a true multi-device experience that allows people to use WhatsApp on other devices without requiring a smartphone connection.

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