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Facebook messenger has a round profile photo with some kind of circle with a coded pattern in it around the photo. I never tried to scan one but I assume you ca

• btym 9y ago
  Snapchat does the same. If you point its camera at someone's profile icon, it will pop up on your phone so you can add them.
• cyphar 9y ago
  Twidere (the free software microblogging client app) supports a similar notion (though I couldn't scan the QR code when I tried.