Bounce tracking mitigation
Bounce tracking (or redirect tracking) routes a user through a tracker's domain mid-navigation so the tracker can set or read its own first-party storage and link the visit across sites. Browsers now detect this pattern and purge the state. This page explains the technique and the mitigations Safari and Chrome apply.
How bounce tracking works
Instead of being embedded as a third party, the tracker inserts itself into the navigation path: a click or redirect briefly sends the user to the tracker's own domain, where it is the top-level (first-party) context and can set or read storage, before forwarding to the real destination. Done repeatedly, this lets the tracker recognise the user across otherwise unrelated sites.
- User is redirected through the tracker's domain
- Tracker acts as first-party during that hop
- Enables cross-site recognition without embedding
How browsers respond
Safari's ITP includes bounce-tracking defences that detect domains used purely as redirect intermediaries and purge their website data. Chrome has shipped bounce-tracking mitigation that identifies stateful bounce trackers and deletes their state. The effect is that storage a bounce tracker sets is short-lived, undermining the technique while leaving genuine first-party state on real destinations intact.
How it appears in analytics and logs
State that disappears after a redirect through a third-party domain is often browser bounce-tracking mitigation purging that domain's storage, not data loss in your own analytics.
Diagnostic use case
Recognise bounce-tracking redirects in your stack and understand why browser purging may erase state a tracker tried to set this way.
What WebmasterID can help detect
WebmasterID does not rely on redirect bounce tracking; its first-party measurement is unaffected by these browser purges.
Common mistakes
- Mistaking browser state-purging for a fault in your own analytics.
- Assuming redirect-based tracking evades modern browsers.
- Treating bounce tracking as a legitimate first-party method.
Privacy and accuracy notes
This page is educational and not an endorsement of bounce tracking. Mitigations reduce a covert cross-site technique; they do not change a vendor's obligations under privacy law.
Related pages
- Safari ITP and analytics privacy
Intelligent Tracking Prevention (ITP) is WebKit's privacy feature that partitions and limits storage to stop cross-site tracking in Safari. It blocks third-party cookies, caps script-set first-party cookie lifetimes, and constrains other client-side storage. This page summarises ITP's documented behaviours and what they mean for measuring audiences.
- CNAME cloaking
CNAME cloaking points a subdomain of your own site (via a DNS CNAME record) at a third-party tracking provider, so the tracker appears first-party to browsers and ad blockers. This page explains the mechanism, the security and privacy risks it introduces, and how browser anti-tracking features have started to counter it.
- Third-party cookie deprecation
Third-party cookie deprecation refers to browsers blocking or phasing out cookies set on domains other than the site a user is visiting. Safari and Firefox already block them by default; Chrome has documented its own plans and shipping changes. This page explains the state of play and what it means for analytics that relied on cross-site cookies.
- Privacy-first analytics
Measurement that needs no redirect bounce tracking.
Sources and verification notes
- WebKit — CNAME cloaking and bounce-tracking defenseSafari/WebKit bounce-tracking mitigation.
- Google — Bounce tracking mitigationsChrome's detection and purging of stateful bounce trackers.
Last reviewed 2026-06-24. Facts are checked against primary/official sources where available; uncertain specifics are marked “Data not yet verified” rather than guessed.