Several services such as YouTube, Plex, and XFINITY use a pattern in which an unauthenticated device displays a code for the user to enter on an authenticated device. When the user enters the code on their authenticated device, their unauthenticated device is then authenticated.

Is there a name for this pattern? I'd love to learn more about best practices when implementing such a login system.

Here are a few screenshots of the process I'm talking about: YouTube Device Pairing Screen Plex Device Pairing Screen

  • I’m glad you posted that picture. From what you were describing, I thought you were describing 2-factor authentication; but I think this would count as something else.
    – zero298
    Commented Jan 12, 2018 at 3:06
  • I don't think this has a specific name, it's a form of authentication UX. Commented Jan 12, 2018 at 9:13

2 Answers 2


As far as I know, it's called Cross Platform Authentication and is a technology originally developed by EBU to interconnect devices and platforms. While development of CPA started around 2013 by BBC, it was approved by ETSI in 2016

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CPA flow


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Single Sign-On

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CPA Project PDF


Back In the old days there was dedicated device to generate this code: Security_token

Some companies name for the token generator app:

I think there is no buzzword for this technology (yet). I would call it "token based authentication", and call part of the site or the app "Authenticator".

  • Those apps are a different pattern though. They're part of multi-factor based authentication using time-based one-time passwords, the implications of which are different from the methods used by Plex and YouTube. For instance, Google Authenticator requires a user to setup the app using a secret key, which is then used to compute the password with the current timestamp. Neither YouTube nor Plex require this setup, so implementing it securely would require different approaches.
    – dstaley
    Commented Jan 12, 2018 at 19:34
  • Agree they are part of the 2-factor authentication, when you try to login from new device. 2 factor auth: 1st step give your username and password, and login with the token. Plex skip the 1st step, and add new device just with the token.
    – Peter
    Commented Jan 12, 2018 at 20:20

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