Glossary

ITP — Intelligent Tracking Prevention

Safari's tracking restrictions: 7-day cookie limits and third-party cookie blocking. What it broke and what it left standing.

ITP (Intelligent Tracking Prevention) is Safari’s set of tracking restrictions, introduced in 2017 and extended several times since.

What it does

  • Caps cookies written by JavaScript at 7 days — and at 24 hours in some conditions. Script-writable storage was later covered too.
  • Blocks third-party cookies — cookies set from a domain different from the page being visited.
  • Stopped treating CNAME-cloaked subdomains as first-party, which removed the common workaround of disguising a tracking vendor’s domain as your own.

What it broke

Anything that relied on a JavaScript-written identifier with a long life, or on identifying users across domains you do not own.

What it left standing

A cookie set by the server, via a Set-Cookie response header, on the domain the user is visiting, in the response that renders the page. That is the whole basis of first-party tracking.

Last updated: 2026-09-21

FAQ

Does ITP affect first-party cookies?+

ITP limits cookies written by JavaScript and blocks third-party cookies. A cookie set by a server response header, first-party, is not subject to the JavaScript limit — which is why server-side first-party tracking is the configuration that survives.

Keep reading

Tracking identifiersHow a click becomes a record you can act on: UTM parameters, click IDs and first-party cookies. What each one identifies, and where each one breaks.Tracking domainThe domain that logs the click and serves the landing page. Why keeping them on the same domain is the whole mechanism.Server-side trackingTracking where the event is captured and processed by your server rather than by a script in the browser. What it fixes and what it does not.

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