Check explainer
3rd-party cookies
Chrome abandoned its 3rd-party cookie phase-out in 2025 in favour of user choice; Safari and Firefox have long blocked them, tracking built on this stays structurally unreliable.
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What we check
Inventories cross-domain sources (script, pixel, iframe) that set third-party cookies.
Why it matters
Chrome abandoned its 3rd-party cookie phase-out in 2025 in favour of user choice; Safari and Firefox have long blocked them, tracking built on this stays structurally unreliable.
Common causes
- Old retargeting and ad pixels from past campaigns keep setting cross-domain cookies.
- Embedded iframes (YouTube, Maps, social widgets) simply bring their third-party cookies along.
- Affiliate and attribution services still work on a third-party basis instead of a first-party subdomain.
- A forgotten chat or personalisation widget loads tracking from third-party domains.
How to fix it
Migrate to server-side tagging and switch attribution to CAPI / Enhanced Conversions.
What does a failing 3rd-party cookies finding mean?
Chrome abandoned its 3rd-party cookie phase-out in 2025 in favour of user choice; Safari and Firefox have long blocked them, tracking built on this stays structurally unreliable. Migrate to server-side tagging and switch attribution to CAPI / Enhanced Conversions.
How do you fix 3rd-party cookies?
Migrate to server-side tagging and switch attribution to CAPI / Enhanced Conversions.