[Beta] User-based cross-platform attribution

What is user-based attribution?

User-based attribution is a cross-platform model that relies on a persistent Customer User ID (CUID) to link conversion events across platforms. Using the CUID, the model attributes all activity to the media source that drove the user’s first conversion or re-engagement event.
 

A cross-platform user journey example

For example, a user clicks a Google web ad, signs up, and completes a purchase on a desktop browser. Later, the same user clicks an Instagram mobile ad, installs the mobile app, and makes another in-app purchase. A week later, the user installs the brand’s CTV app, signs in using the same CUID, and starts a paid subscription there as well.

Because the CUID consistently identifies the user across platforms, and the Google web campaign was the first non-organic launch event associated with that CUID, all subsequent activity - including the mobile app purchase and the CTV subscription - is attributed to the Google campaign.

User-based vs. device-based attribution

This model addresses a key limitation of device-based attribution: treating each device as a separate user and fragmenting the user journey across platforms. By contrast, user-centric attribution links events across devices using a persistent CUID, enabling consistent measurement, accurate campaign crediting, and a true understanding of lifetime value across the entire product line.

The following user journey example illustrates the difference between device-centric and user-centric attribution:

A user clicks a Meta ad on the web, is redirected to the advertiser's website, signs up, and creates an account. Later, the same user installs the advertiser's iOS app, logs in, and makes a $50 purchase. A few days later, the user sees a YouTube ad, installs the advertiser's PC app, logs in again, and makes a $100 purchase.

Device-based attribution credits $0 to Meta Ads, while user-based attribution credits $150. The table below shows how this journey would be attributed under each model:

What makes an event a candidate for cross-platform attribution?

An event is considered a candidate for cross-platform attribution if it meets all of the following conditions:

• CUID is present: The event must include a valid Customer User ID (CUID) — a persistent, advertiser-provided identifier (e.g., login ID or hashed email) that uniquely identifies a user across devices and platforms. 
  • If an event is missing a CUID but shares the same appsflyer_id, AppsFlyer can backfill the CUID within a short processing window — up to 4 hours before the first event that arrived with a CUID. For more information, see The CUID enrichment processing window below.
  • Events that arrive without a CUID and can’t be enriched through the CUID enrichment process are still included in cross-platform attribution. In these cases, attribution is determined using their device-level (classic) attribution method.
• Belongs to a product line: The app generating the event must be part of a product line – a grouping of related apps (e.g., iOS, Android, CTV) under the same brand, for which attribution is scoped and configured collectively. For more information, see Group apps for cross-platform attribution.
• Within the inactivity restoration window: The event must fall within the inactivity window – a configurable period (e.g., 7 to 390 days) during which a CUID is still considered active and eligible for attribution within a given product line. If the CUID has not been seen within this window, its previous attribution mapping is discarded. 
• Device-level attribution fields are present: The event must already contain valid device-level attribution parameters (e.g., media source, campaign ID) derived from AppsFlyer’s classic device-based attribution model.

How is the attribution source determined?

This model attributes all events for a given user (CUID) to the original media source that drove the user’s first conversion.

The attributed original media source is determined using the following logic:

• For each in-app event with a CUID in a product line, AppsFlyer identifies the earliest launch event for that CUID (i.e., a launch event with a valid media source).
• The media source attributed to that launch event by classic device-centric attribution is considered the attribution source for the in-app event.
• This media source is used as the user acquisition cross-platform attribution source for all subsequent events associated with that CUID and product line.
• If an in-app event lacks a CUID, AppsFlyer attempts to backfill it during the 1–4 hour enrichment processing window. 
• If an event without a CUID arrives outside the defined CUID enrichment window, it will still be included in cross-platform attribution. These events are attributed using their device-level (classic) attribution method.

The CUID enrichment processing window

The CUID enrichment processing window is the period (1–4 hours) during which AppsFlyer processes newly arrived in-app events to backfill missing customer user IDs (CUIDs). This enables cross-platform attribution even if some in-app events arrive without a CUID.

How does CUID enrichment work

• Every 1–4 hours, AppsFlyer runs a processing job.
• If an event arrives without a CUID but shares the same appsflyer_id as another event with a CUID, AppsFlyer backfills the missing CUID.
• This stitching applies only to events received during the processing window.

CUID enrichment Example

• 8:01: A first app open event is recorded with appsflyer_id = XYZ.
• 9:00: A sign-up event is recorded with cuid = 123 and appsflyer_id = XYZ.
• 12:00: The 4-hour processing window ends. AppsFlyer retroactively stitches cuid = 123 to the first app open event.
• 12:30: A purchase event with appsflyer_id = XYZ  is recorded but has 
• no CUID. Because the event arrives after the window closes, AppsFlyer does not stitch cuid = 123 to it.

CUID enrichment Limitations

• Events without a CUID arriving outside the 1–4 hour processing window are attributed using classic AppsFlyer attribution and added to the cross-platform attribution method results.
• CUID stitching is not applied retroactively beyond the processing window.

Set up cross-platform attribution

To set up cross-platform attribution, you need to apply a few settings in AppsFlyer and implement specific SDK functions in your app code. 

• In AppsFlyer, assign your apps to a product line, opt in to cross-platform attribution, and specify the inactivity restoration window. For more information, see Set up a product line.
• In your app, set the AppsFlyer SDK to send events with CUIDs. For developer instructions, see Set Customer User ID.

View cross-platform attribution results

• Report: To view cross-platform attribution results, see the Data Locker End-user events cross-platform report.

• My Dashboards: Available via the "Cross Platform" template. For more information about selecting a dashboard template, see Create a custom dashboard.