WhatsApp’s latest beta version lets you add contacts by scanning their QR codes, WABetaInfo
It’s a minor feature, but adding contacts on WhatsApp can be a pain. At the moment, the service relies on you adding a new contact to your phone’s address book, which creates an annoying extra step when you just want to be able to message someone in WhatsApp itself. QR codes are a much more convenient way of adding someone if you’re with them in person, although it won’t make the process too much easier if you’re doing it online.
Although the feature is currently available in beta, there’s no word on when we might see it come to the main app. If you want to join the beta on Android, I was able to sign up using this link and verify that the QR code option can be found in settings, however the iOS beta is reportedly closed.