WhatsApp’s multi-device support is now available in public beta, so you can use it on any device you want without your phone being connected to it.
Whatsapp Multi Device Beta Update! Here's How to Use It – WhatsApp Linked Devices
According to a recently updated FAQ page, the new opt-in program will allow up to four companion devices at a time. The multi-device beta is available for use with the latest version of the WhatsApp app on both Android and iPhone devices.
WhatsApp stated that you can still only link one phone to your WhatsApp account at a time and that you will have to manually link your new devices to your phone using the correct WhatsApp account.
The company also said that the multi-device feature doesn't currently support tablets, so you won't be able to use WhatsApp on your iPad. However, WhatsApp CEO Will Cathcart previously confirmed to WABetaInfo that WhatsApp on iPad would come eventually.
