Firefox Enhanced Tracking Protection
Enhanced Tracking Protection (ETP) is Firefox's default privacy defence: it blocks resources on a known-tracker list and, through Total Cookie Protection, partitions cookies into a separate jar per website so they cannot be shared across sites. This page explains what ETP blocks and how it shapes analytics data from Firefox users.
Blocklist and storage partitioning
ETP blocks network requests to domains on a curated tracking-protection list (sourced from Disconnect) and partitions storage so a cookie set on one site cannot be read on another. Total Cookie Protection extends this by confining cookies to a per-site jar, which neutralises third-party cookies as a cross-site identifier even when they are not on the blocklist.
Firefox also offers stricter modes and query-parameter stripping that remove some tracking parameters from URLs.
What it means for analytics
If your analytics or tag manager request resolves to a domain on the tracker list, it can be blocked outright in Firefox, so those events never arrive. Even when requests succeed, partitioned cookies mean third-party measurement cannot stitch a user across sites. First-party, same-site analytics is the measurement that continues to work.
- Requests to listed tracker domains can be blocked
- Total Cookie Protection isolates cookies per site
- Cross-site third-party measurement does not persist
How it appears in analytics and logs
Missing hits from a known-tracker domain or absent cross-site joins for Firefox traffic typically reflect ETP's blocklist and Total Cookie Protection, not a tagging fault.
Diagnostic use case
Understand why some analytics and tag requests are dropped in Firefox, and why cross-site identifiers do not persist for Firefox users.
What WebmasterID can help detect
WebmasterID's first-party, non-tracker model is less likely to be blocked by tracker blocklists than third-party tracking scripts.
Common mistakes
- Assuming blocked tracker requests are a tagging bug.
- Expecting third-party cookies to join sessions across sites in Firefox.
- Ignoring query-parameter stripping when reading campaign data.
Privacy and accuracy notes
ETP is on by default to protect users. This page is educational and describes documented behaviour; it does not endorse circumventing tracker blocking.
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.
- Chrome Privacy Sandbox and analytics
The Privacy Sandbox is a set of Chrome web-platform APIs intended to support advertising and measurement use cases without cross-site tracking of individuals. It includes interest-based targeting, conversion measurement, and anti-abuse APIs that return aggregated or noised results rather than per-user identifiers. This page maps the pieces and what they mean for analytics.
- Cookieless analytics: how it works and its limits
Cookieless analytics records visits and events without setting cookies or persistent cross-site identifiers. It relies on first-party, server-side signals and aggregate counting. The trade-off is honest: it cannot follow an individual across sessions the way cookie-based tracking can — which is exactly the point for privacy-first measurement.
- Privacy-first analytics
First-party measurement that avoids tracker blocklists.
Sources and verification notes
- Mozilla — Enhanced Tracking Protection in FirefoxWhat ETP blocks and its protection levels.
- Mozilla — Total Cookie ProtectionPer-site cookie jars by default.
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.