WhatsApp now supports multi-device login. That allows four devices per account. Mark Zuckerberg revealed the functionality on Facebook and Instagram.
“Today, you can log into the same WhatsApp account on up to four phones,” he stated.
Users formerly had one account per device. The web client only worked if their phone was online. The latest deployment syncs their communications across devices. In addition, the app is accessible on multiple devices, even if one is off.
In 2021, beta testers tested multi-device compatibility.