WeChat (A very popular communication app, ~550 million active users) uses QR codes as a way to add contacts. The app will display a QR code and people you have

WeChat (A very popular communication app, ~550 million active users) uses QR codes as a way to add contacts. The app will display a QR code and people you have just met can scan the code to send a friend request. People use this feature quite a bit. It saves time over ensuring that the other party is typing your name correctly.