I uninstalled and reinstalled Uber, how does it still know who I am?

I had uninstalled the Uber app on my iPhone. I do not have Uber Eats or another app install which appears to be related to Uber.

Also, I do NOT use iCloud.

Today I reinstalled Uber and found I am fully logged in.

By what mechanism specifically did Uber persist my account information while the app was uninstalled?

Solution 1:

Another possibility is the iOS keychain. Apps can create entries in the keychain which persist after the app is deleted. Unfortunately, there is no supported way to purge this information (beyond resetting the device).

Keychain entries may also be app group entries, which may be set/cleared by multiple apps provided by the same developer.

App developers are forbidden from reading the imei on iOS.