App Tracking Transparency (ATT)
App Tracking Transparency, usually shortened to ATT, is Apple's iPhone rule that an app must ask before it follows a person across other companies' apps and websites. Tracking here means linking what you did in one app to what you did in another company's app or site. Most people tap "Ask App Not to Track." After that, ads tools see much less about who saw the ad and who bought.
Theodor Lindfors, Founding Marketer ·
How ATT works
An app that wants to track across other companies' properties must show Apple's App Tracking Transparency (ATT) prompt and get an explicit yes. Without it, the identifier for advertisers (IDFA, a device ID used to match ads to installs) is unavailable. The permission is per app, and users can review it in settings at any time.
Let's take a software company as an example. They sell a job-site phone app to plumbing businesses as a monthly subscription. The phone app is what plumbers use on job sites to look up customers, log visits, and send invoices. The software company advertises the app on Meta so more plumbers will download it.
Let's take a software company as an example. They sell a job-site phone app to plumbing businesses. A plumber installs the app. The app shows Apple's App Tracking Transparency (ATT) prompt: Allow this app to track your activity across other companies' apps and websites? Most people tap Ask App Not to Track. After that, Meta cannot use the plumber's identifier for advertisers (IDFA, a device ID used to match ads to installs) to say this Meta ad led to this install. The ad still ran. The install still happened. The clean link between them is gone.
Why ATT matters for marketers
Cross-app measurement used to be straightforward: one identifier followed the person from ad to install to purchase. App Tracking Transparency (ATT) ended that for anyone who declines, which is most people. A job-site app's Meta ads manager used to show a neat install count. After App Tracking Transparency, that count is smaller, later, and more modeled.
The consequences were practical. Reported conversions fell, in-platform attribution (which ad gets credit) got shorter and less certain, and audiences built on cross-app behavior shrank. Investment moved toward SKAdNetwork (SKAN: Apple's aggregated install reports), server-side event sharing, and modeling.
How to work with ATT
Lean on measurement that does not depend on cross-app identity: your own first-party data (information a software company collected from plumbers who signed up), holdout tests, and blended efficiency such as MER (marketing efficiency ratio: total revenue divided by total ad spend).
Server-side event sharing like Conversions API (CAPI: sending purchase or install events from your server instead of the browser) helps with events the browser drops, but it does not override an App Tracking Transparency (ATT) decline. Different problem, different fix. A plumber saying no on the iPhone is not undone by a server ping.
Common ATT mistakes
- Expecting pre-App Tracking Transparency (ATT) reporting accuracy to come back. It will not.
- Comparing today's job-site app conversions to a 2020 baseline.
- Treating Conversions API (CAPI) or server-side tagging as a way around the App Tracking Transparency (ATT) permission.
- Dropping iOS entirely because it is harder to measure, without testing whether it still sells.
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