Appgain Knowledge Hub for Digital Marketers.

SKAdNetwork (SKAN)

How does it work? We’ll begin with the four main players involved, each having specific roles and responsibilities to ensure a smooth operation: 

  1. Publishing app – where the ad is displayed.
  2. Ad network – that connects app advertisers to publishers.
  3. Target app – the app that is being advertised.
  4. Mobile measurement partner (MMP) – responsible for connecting all the dots by attributing and optimizing app data and campaign performance metrics. Holistic SKAdNetwork management allows marketers to measure, visualize, and optimize with ease.

There are two types of engagements that SKAdNetwork registers: 

  1. Views – whether an ad was viewed
  2. StoreKit renders – whether or not a StoreKit rendering was generated.

The SKAdNetwork flow An ad is displayed in the publishing app. As soon as the ad is displayed, the publishing app starts the 3-second timer and notifies SKAdNetwork that it has started.

  1. If the ad is displayed for at least 3 seconds, the publishing app will then notify SKAdNetwork that the 3-second timer is up and this activity will be recorded as a successful view. If the user engages with the ad, the publisher renders the advertised app StoreKit. 
  2. Once it is displayed, SKAdNetwork registers that the StoreKit was rendered successfully. The next step would hopefully be for the user to download the advertised app. 
  3. If the StoreKit was rendered, the user can download the app right then and there. If the user installs the app and launches it within the SKAdNetwork attribution window, the install is attributed to the ad network and the device sends the install postback to the ad network and a copy to the advertiser.
  4. For SKAdNetwork, the attribution window can be up to 30 days between click and install depending on the ad type. Unlike standard postbacks, SKAdNetwork postbacks are not immediately sent to the ad network and advertiser when the app is first launched. 
  5. The SKAdNetwork postbacks are built on a timer mechanism that only sends the postbacks when the timer runs out. This timer delays the postback by a minimum of 24 hours. Once the timer runs out, the ad network and advertiser receive the postback. 

It’s important to note that postbacks don’t contain any device or user data, and together with the timer delay, ensure that users’ data remains private by disabling the ability to single out a specific user.

If the advertiser is working with an MMP, like AppsFlyer, postbacks will be reported to the MMP via dedicated dashboards and APIs, or directly via a configuration of the MMP as an endpoint by the advertiser.

The challenges – and how to address them

SKAdNetwork does present new functional challenges for advertisers.

To name a few:

  • No real ROI/LTV – SKAdNetwork measures mostly installs, conversion values and post-install data, but in a very limited, time-restrictive way
  • Granularity – Data is limited to campaign level and only to 100 campaigns
  • Postback delay – Postbacks are delayed by at least 24 hours, limiting immediate campaign optimization
  • Ad fraud risk – Data can easily be manipulated in transit
  • No re-engagement attribution support

There’s no doubt that compared to previous methods of attribution, SKAdNetwork does bring with it a set of limitations, complexities, and restrictions. 

Fortunately, there are ways to navigate these challenges to retain the ability to measure and predict the value of your acquired users. 

The key to unlocking value from SKAdNetwork is to understand Apple’s unique conversion value mechanism.

Conversion values – and how to make them work for you Conversion values are configured by app developers to measure post-install activity, and tie it back to the install. A single conversion value is included in the one-time postback that Apple sends to the ad network and advertiser. 

As a result, the information in this conversion value is all the information you can get on a user’s post-install activity (assuming they didn’t consent to “tracking”), making it extremely important. After all, in a freemium world, optimization is driven by post-install data.

A conversion value is defined by 6 bits, which are binary measures, meaning they can be turned on or off (0 or 1). This opens up the potential for 64 measurement combinations within those 6 bits – from 0 to 63.

Although 64 options can be considered limited, there are still plenty of options to work with to measure revenue, engagement, funnel progress and more. 

As long as you properly map your conversion values based on your internal logic, these values can be used in any way you want. They’re yours to control and assign to the KPIs that are most valuable to you. 

The 64 values, each with their own unique decoding configured by the app developer/advertiser, are then attributed to the source of the install, enabling campaign measurement and optimization.

How are marketers in different verticals mapping their conversion value schemes? 

What we can learn by analyzing data from AppsFlyer’s Conversion Studio is that Gaming apps are laser-focused on revenue, and as such – it’s a model that’s being involved in most conversion value schemes. On the non-gaming side, in-app activity is the most configured option.
For more on how to make the most of conversion values, including benchmarks on activity window timer, and optimal usage of the 64 combination capacity, click here.

iOS 15 updates

Conversion value endpoint configuration

Before iOS15, SKAN postbacks were sent only to the ad networks, and then forwarded to the advertiser or MMP on the advertiser’s behalf. 

In Apple’s latest iOS15 update, advertisers have been granted direct access to SKAdNetwork postbacks, giving them the ownership they deserve of their data. 

By configuring their MMP as an endpoint, the MMP:

  • Provides advertisers with full flexibility for designing, testing, managing, and optimizing their conversion value logic
  • Validates the postbacks against those reported by the ad network
  • Connects ad network campaign name, ad set name, and ad name to the SKAdNetwork-reported campaign
  • Connects pre-install campaign data such as cost, clicks and impressions
  • Provides the data in SKAdNetwork dashboard as well as SKAdNetwork APIs
  • Prevents and blocks SKAdNetwork fraud

Private Relay and Deferred Deep Linking

Announced during WWDC21, all iCloud Plus users have beta access to Private Relay, a new privacy service for Safari users on iOS15. The service hides and encrypts the user’s IP address, which doesn’t allow for deferred deep linking and attribution data for app developers. 

Deferred deep linking is the process where users who have not installed an app are directed to a specific page or activity in the app after the app is installed and launched. This is critical when creating contextual, post-install experiences to increase conversion rates.

Access to Private Relay is limited, but Apple’s trend towards increasing privacy is clear. Advertisers can utilize AppsFlyer’s Private Relay solution, an off-the-shelf App Clip framework to continue collecting attribution data without compromising privacy or security.

SKAdNetwork 4.0 (SKAN 4.0)

On October 24, 2022, Apple released the next version of SKAdNetwork (4.0), which introduces significant changes that allow advertisers and ad networks to measure more while maintaining user privacy.

Three postbacks instead of one

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, like so: 

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 earlier versions 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).

How does it work?

When crowd anonymity is low, the conversion value is masked. When crowd anonymity is medium, postbacks include a coarse conversion value. And when crowd anonymity is high, postbacks 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 is included in the 1st postback only.

Hierarchical source identifier

From SKAN 4.0 onward, Apple is 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.

Web-to-app support

Previously, advertisers could only measure app-to-app flows, but web-to-app was not supported. In SKAN 4.0, Apple supports web-to-app attribution for Safari.

Find out more about SKAN 4.0 changes and building your strategy

How can advertisers make the most of SKAdNetwork?

Here are a few steps to ensure your business is SKAdNetwork-ready:

  • Data aggregation – Be sure to collect all SKAdNetwork information from each ad network.
  • Data validation – Ensure all postbacks are signed by Apple and aren’t manipulated in transit. Working with a trusted MMP can help you address this with ease.
  • Data enrichment – Match SKAdNetwork information with other data points, such as impressions, clicks, cost, organic traffic and more, for complete ROI analysis.
  • Data enablement – Facilitate SKAdNetwork data for convenient consumption by the advertiser through dedicated dashboards and APIs.
  • Seamless integration – Make sure your mobile attribution solution offers full encapsulation, which requires close to zero effort from the advertiser, especially when it comes to future changes in the SKAdNetwork protocol.
  • Conversion events – Be sure to measure server side, dynamic, and flexible in-app events.

Key takeaways

  • As the industry continues to adapt to a privacy-centric reality, the ability to measure, attribute, and optimize will continue to improve. Indeed, measurability has been mostly retained with improvements driven by better models, increased usage of predictive analytics, acquired expertise in SKAN, and innovation across the ecosystem. 

On an advertiser level, you should:

  • Leverage easy to use tools to map/constantly update your conversion value schema to make the most of the 64 options instead of wasting time on development.
  • Use predictive analytics to overcome time limitations and leverage early signs of engagement to predict long-term campaign performance. Put mobile attribution in SKAdNetwork on “autopilot”, removing measurement and timing barriers, so you can maintain and strengthen your competitive edge in this new reality.
  • Keep your data safe from all types of fraud in the new iOS 14 ecosystem. An MMP can offer protection from SKAdNetwork fraud, by ensuring that you’re getting accurate data on your campaign performance. It protects your ad spend before, during and after installs, with end-to-end coverage against infrastructure weaknesses, data limitations and reporting loopholes.
  • Connect with an ecosystem – partner with an MMP that has joined forces with ad networks such as Facebook, Twitter, Snap and ironSource. Solid cooperation ensures that postbacks, conversion value schemas and data are delivered to your MMP and chosen partners smoothly and easily.