Is it possible for two different users to have the same device ID? I understand it's possible if they use the same computer/ device to log in, but what if they don't? Is Device ID completely reliable in terms of being unique for every device?

  • 2 August 2022
  • 1 reply

Device ID as Unique Identifier 


Best answer by Zhenia Semenina 4 August 2022, 14:32

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Hey there,

Thanks for writing in, happy to clarify! 


Device IDs are unique to individual devices which in turn are assigned to a unique user profile. They do not change on a new session, when the app is reinstalled, or after a certain amount of time passes. The IDs are recognized by our SDKs and will be assigned to any event fired from that device, unless the device ID is reset under the following circumstances:

On iOS, if a user manually resets their IDFA, or if they limit ad tracking the IDFA will send as all zeros, and we cannot recognize the unique device.

On Android, if a user resets their AdID.

On Web, if a user deletes their cookies, the randomly generated UUID will be reset and saved again.


Two other circumstances a device ID will be changed - if the user has limited ad tracking, a random device ID will be assigned for each install, or if the user clears app data manually. 

So there is no reason outside of user action that a device ID would change.