WhatsApp does let you link your account to another device, and they can access your account without needing internet. However, that’s not quite like syncing your messages to an account and being able to simply log in to another device.
But WhatsApp might let you add secondary device to your account
This was discovered in a beta version of the app, so it’s not available to the public just yet. Also, this also means that there’s a chance that this feature won’t ever see the light of day. When you enable this feature, you’ll be able to log in to your account on another device. Once logged in, your messages will be copied over to that device. You’ll know this is happening because a dialogue will pop up on the top of the screen. Based on how many messages you have, it may take a while to copy all of your messages over. While the app is still transferring the messages you won’t have access to your old messages. You can write new messages, but you won’t see your old ones until the syncing is complete. We’re not sure at this point if WhatsApp will keep the secondary device constantly synced. There could be a chance that the app will sync the messages at a certain time just like backing up the messages. However, that’s just speculation. This feature could be great for people who have multiple devices and don’t want to stick to one. It could be useful having more than one device to message people. The secondary device could be a tablet, and that will lead to a better typing experience. We don’t know when this feature will come out, so you’ll need to keep an eye out for it.
