Intent to prototype: Bounce Tracking Mitigations

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Paul Zühlcke

May 6, 2024, 11:08:11 AMMay 6


Browser tracking protections, such as third-party cookie restrictions, can be bypassed using bounce tracking which uses short-lived top level redirects to persist first-party state. Gecko already ships Cookie Purging to mitigate this. We intend to prototype Bounce Tracking Protection - a new standardised variant of Cookie Purging that uses heuristics to detect bounce trackers, rather than relying on tracker lists.

We plan to enable the feature in Firefox Nightly by the end of the week. Please let me know if you have questions or concerns. You can also find us in #anti-tracking on Matrix.

Bug: Bug 1839915 [meta], Bug 1895222 - Enable in Nightly

Specification (draft):

Platform coverage: Firefox Desktop, Android (Fenix)


Enable the feature: privacy.bounceTrackingProtection.enabled = true
Enable tracker data purging: privacy.bounceTrackingProtection.enableDryRunMode = false

DevTools bugs:

Link to standards-positions discussion:

Other browsers:

web-platform-tests: Not implemented yet, blocked on The feature has Gecko tests.

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