Customer user ID field (CUID)

At a glance: Cross-reference your in-house data with AppsFlyer attribution data by the Customer user ID (CUID) field.

Implementing the CUID

The Customer user ID (CUID) field is a unique user identifier set by app and website owners.

  • CUID is reported by you to AppsFlyer using AppsFlyer APIs or SDKs.
  • AppsFlyer populates the CUID field in raw data reports accordingly.
  • Use the CUID to cross-reference AppsFlyer attribution data with your other data using the CUID as a key.
  • Example: A user with two devices has the same CUID ("1234567"). Each time they perform an event on a device, it is recorded along with the CUID. This enables the advertiser to aggregate both devices' raw data into a holistic view of the user.
  • CUID is used by AppsFlyer Audiences and People-Based Attribution solutions for improved accuracy and targeting.

CUID design and privacy

CUID implementation considerations

Mobile SDK

  • Set the CUID in the SDK (Android, iOS) as soon as possible. Do so because events sent before this won't have the CUID. The CUID can't retroactively update events recorded without a CUID. 
  • So that the CUID is part of the original attribution data, set the CUID before calling the start method API.
  • If you work with integrated data partners, such as Mixpanel or Swrve, the CUID must be set for the integration to work effectively.

Delay SDK init for customerUserID

  • You can delay the SDK Initialization until the CUID is set.
  • This feature ensures that the SDK doesn't begin functioning until the CUID is provided. If this API (Android, iOS) is used, in-app events and other SDK API calls are discarded until the CUID is provided.

Use this API after considering your business logic and the following pros and cons:

  • Pros:
    • Attribution data is always associated with a CUID.
    • Use the CUID to associate attribution data with other data you have in your systems. 
    • This allows a more sophisticated use and processing of the data that you get from AppsFlyer.
  • Cons:
    • Actions and events that users perform, including purchases and subscriptions, aren't recorded in AppsFlyer until CUID is set. This can lead to discrepancies and increases exposure to fraud.

People-Based Attribution

AppsFlyer People-based Attribution (PBA) gives you a broad perspective on the impact of web and mobile campaigns, as well as the ability to analyze your efforts to switch web users to your mobile app and vice versa.

You must set the same CUID in both mobile and web environments to enable cross-platform insights and analytics. 

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