Welcome to SKAdventure 4.0

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Not sure what SKAdNetwork 4.0 is all about? Let’s cover the basics.

3 postbacks instead of 1

SKAdNetwork 4.0 enables advertisers to receive up to 3 postbacks, each based on a specific activity window (0-2 days, 3-7 days and 8-35 days). This allows advertisers to understand how users engage with their app over time.

The first postback is sent within 24-48 hours as before. However, the length of the timer increases for the second and third postbacks, which are sent after 24-144 hours.

Although it’s important to note that these three postbacks cannot be connected and tied to a specific user, advertisers are still able to count unique event occurrences.


Although each postback is based on a limited activity window, SKAN 4.0 also introduces a new ability called ‘LockWindow’ which allows app developers to finalize the conversion value and lock the measurement window in order to receive postbacks sooner. For example, app developers can lock the window of the second postback anywhere between day 3 and day 7.

Crowd anonymity

Crowd anonymity is a new term that Apple uses to describe the privacy-preserving way in which SKAN delivers attribution data. In short: the more installs you get, the more data you get.

To ensure that user privacy is kept, Apple limits the data that SKAN shares in postbacks. Postback data tiers are based on the conversion-volume of the campaign. There are four tiers of crowd anonymity: 0, 1, 2 and 3.

Apple decides which crowd anonymity tier each install belongs to, and shares data accordingly. For example, if the install belongs to tiers 0 or 1, the postback will include only a coarse conversion value and a 2-digit source identifier (read more about source identifiers below).

Hierarchical conversion values

In the current version of SKAdNetwork, postbacks include a conversion value only in cases where Apple’s privacy threshold is met. When crowd anonymity is low, Apple takes extra precautions to protect user privacy by masking the conversion value and source app ID.

SKAdNetwork 4.0 introduces a new set of “coarse-grained” conversion values (in addition to the “fine-grained” 64 values that exist today).

Coarse-grained conversion values are split into 3 types: low, medium, or high. These values are assigned by the advertiser to indicate different levels of user engagement, and allow advertisers to receive at least some attribution data in cases where the privacy threshold is not met (at lower levels of crowd anonymity).

When crowd anonymity is low, the conversion value will be masked. When crowd anonymity is medium, postbacks will include a coarse conversion value. And when crowd anonymity is high, postbacks will include a fine conversion value.

Coarse-grained values are provided in the 2nd and 3rd postbacks, or in the 1st postback if the privacy threshold is not met; whereas the fine conversion value will be included in the 1st postback only.

Hierarchical source identifier

From SKAN 4.0 onward, Apple will be renaming its campaign identifier field to source identifier and increasing its range from 2 digits (representative of 100 options) to 4 digits (representative of 10,000 options).
Although the source identifier is a single number, Apple encourages advertisers to use it as 3 hierarchical numbers — allowing them to measure more parameters, such as ad placement, GEO, creative, and more.

As with hierarchical conversion values, hierarchical source identifiers also adhere to Apple’s privacy threshold — meaning the higher the level of crowd anonymity, the higher the level of provided granularity. 

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