How to Stop Apps Tracking You Across Other Apps

Published August 14, 2026 · Last reviewed September 2, 2026

What “tracking” means here, precisely

Apple defines tracking narrowly: linking data collected about you in one company's app with data collected about you elsewhere — other companies' apps, websites, or offline datasets — for advertising or data-broker purposes. The mechanism is usually the advertising identifier (IDFA), a device-level code that multiple apps can read, giving otherwise unrelated companies a shared key to join their records on.

Being precise matters because the phrase is used loosely elsewhere. An app measuring what you do inside that app is analytics, not tracking under this definition, and it is unaffected by this setting.

The one switch, and the second one people forget

1. Open Settings, tap Privacy & Security, then Tracking.
2. Turn off Allow Apps to Request to Track. Existing permissions are revoked and future prompts never appear.
3. Confirm the app list underneath shows nothing with tracking allowed.
4. Go back to Privacy & Security, scroll to Apple Advertising, and turn off Personalised Ads.

The second step is separate because it governs Apple's own advertising in the App Store and News, which is not covered by the tracking switch. Turning it off does not reduce the number of ads you see; it stops them being targeted using your Apple ecosystem activity.

What this stops, and what it does not

The habits that matter more than the switch

Action

Use Sign in with Apple, and choose Hide My Email, when an app offers it.

Why it helps

It removes the identifier you would otherwise hand over voluntarily, which is the gap the tracking switch cannot close.

Verification

The app shows a relay address ending in privaterelay.appleid.com rather than your real address.

Action

Decline the loyalty-card prompt that asks for a phone number at checkout, or give a dedicated number.

Why it helps

In-store purchase history joined to your phone number is a data-broker input that no phone setting can affect.

Verification

Nothing to check on the phone — this is a habit, not a setting.

Action

Review the tracking list once after a big app-install spree.

Why it helps

The master switch handles new installs, but it is worth confirming nothing was allowed during a period when the switch was on.

Verification

The list under Tracking is empty.

Does turning it off cost you anything?

Ads become less relevant; they do not disappear or increase. Some free apps show a message asking you to allow tracking to “support” them — that is a request, not a requirement, and declining does not restrict the app. There is no measurable performance or battery cost either way.

How it works

Before App Tracking Transparency, every app on a device could read the same advertising identifier. Because it was identical across apps, two companies who had never shared anything else could match their records simply by comparing that string — which is how a search in one app became an ad in another. The identifier was the join key for an entire industry.

The framework works by making that key unavailable by default. An app must call a system API to request tracking permission, and until you grant it, the identifier the app receives is a string of zeroes — indistinguishable across all users, and therefore useless for matching. Turning off Allow Apps to Request to Track makes that denial automatic and permanent: the prompt never appears, and every app gets zeroes.

The limits follow from the mechanism. Removing a shared key stops device-level joining, but it cannot stop joining on identifiers you supply yourself. An email address, a phone number, or a loyalty account number works exactly as well as an advertising identifier for matching records — better, in fact, because it survives changing your phone. Apple's policy prohibits developers from fingerprinting as a substitute, but policy is enforced by review rather than by the operating system, which is a weaker guarantee than the technical one.

Worked example

An iPhone with the tracking switch on. Under Tracking, eleven apps are listed as allowed — a news app, three games, a food-delivery app, two retailers, and several utilities, most granted during onboarding when the prompt appeared alongside other setup dialogs and was tapped through.

The owner turns off Allow Apps to Request to Track. All eleven grants are revoked at once, and the list empties. They then turn off Personalised Ads under Apple Advertising. Total elapsed time: under a minute.

Two weeks later the practical result is mixed in an instructive way. Ads in the free games are visibly less relevant, which is the intended effect. But an ad for a specific pair of running shoes, browsed on a retailer's website in Safari while logged in, still appears in that retailer's app — because the retailer knows the same account browsed and the same account opened the app. No device setting can sever that link. It is a useful reminder that the switch removes one mechanism, not the whole practice, and that Safari's own tracking controls and a habit of not logging in do the rest.