Session counting and the af_app_opened event explained

At a glance: Each time an app launches or displays in the foreground, the app sends an af_app_opened event. 

Session counting

  • af_app_opened is an automatic SDK event used to count sessions.
  • The event provides advertisers with the ability to record and attribute sessions to a media source and campaign. The event is sent as a postback to the ad network.
  • Session data can be found in the Activity, Overview and Cohort pages. The Retention report displays unique daily/weekly sessions by users. 
  • Raw data: Since af_app_opened is a frequently occurring event, it does not appear in downloaded or pulled data reports, aggregated or raw. However, sessions raw data is available in Data Locker.

Sending af_app_opened to ad networks

No coding is required to implement the event since it is handled automatically by the Appsflyer SDK. It is available to networks supporting in-app events. The event value has no meaning.


  • The af_app_opened event is a frequent event and may create a high volume of postbacks.
  • In-app events mapping > map all SDK events: mapping all events does not include af_app_opened.

Installs and sessions

According to AppsFlyer's attribution model, an install becomes final once the user launches the app. These first install sessions are not counted in the regular session count. Which means:

Total number of sessions per media source = number of installs + number of sessions.

For example, a user installs an app and launches it on Sunday. On Monday, the user launches the app again. The number of sessions recorded for this user is 1, and the total number of sessions including the install session is 2.

Session counting SDK methods

You can use an SDK method (Android, iOS) to set the minimum time between sessions, to count as two separate sessions.

In Android, you can also report new sessions manually, while the app is running. This is especially useful for Android utility apps, which run in the background. 

Retargeting sessions

  • Retargeting sessions occurring on or after July 13, 2020, are available.
  • The retargeting sessions are available in:
    • The relevant Cohort views, meaning retargeting and unified. 
      • In the case of the unified view, if sessions were attributed to a UA and retargeting media source, the retargeting media source prevails, and the UA media source is not displayed. 
      • Data freshness: Daily 13:00 UTC.
    • Data Locker: Retargeting sessions reports can be enabled; they include both re-engagement and re-attribution sessions. 
      • Data freshness: 6-hour lag.

Re-engagement session postbacks

When existing users re-engage with an app, a re-engagement window opens. When the window is open, events, including af_app_opened, are sent to both the original network and retargeting network.

In the case of Google Ads and Twitter, to avoid duplicate postbacks, the af_app_opened event is sent once.

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