We Tested 9 Analytics Tools Against Every Major Ad Blocker

Roughly 30% of European internet users run an ad blocker. That is not a fringe behavior — it is nearly a third of your audience. If your analytics tool is blocked, those visitors disappear from your data entirely. No pageviews. No conversions. No attribution. And this happens on top of the traffic you already lose to consent banner rejection.

We wanted to know exactly which tools survive and which do not. So we tested 9 analytics platforms against the 5 most widely used ad blockers with a simple, reproducible methodology: does the analytics request reach its endpoint, yes or no?

What we tested

We selected the five ad blockers with the broadest install bases, covering browser extensions, built-in browser protections, and behavioral blocking:

• —uBlock Origin — the most popular extension-based blocker, with approximately 40 million users
• —AdBlock Plus — the legacy dominant blocker, approximately 100 million users
• —Brave Shield — built into the Brave browser, approximately 70 million users
• —Firefox Enhanced Tracking Protection — Mozilla's built-in protection in Strict mode, enabled by default for millions of Firefox users
• —Privacy Badger — developed by the EFF, uses behavioral analysis rather than static blocklists

Together, these blockers represent over 300 million installations. They also cover every major blocking strategy: static filter lists, browser-level domain blocking, and machine-learning-based behavioral detection.

The results

Each cell is binary. Pass means the analytics request reached its collection endpoint. Blocked means it did not.

Three tools — GA4, Adobe Analytics, and PostHog — were blocked by every single ad blocker we tested. Piwik PRO and Mixpanel were blocked by 4 out of 5. Even privacy-focused tools like Plausible and Fathom were blocked by 3 out of 5 — their domains appear in the EasyPrivacy filter list that uBlock Origin loads by default. Only one tool passed all five tests.

Why some tools survive and others do not

The pattern is straightforward. Every tool that failed loads a client-side JavaScript file from a known tracking domain — google-analytics.com, cdn.mxpnl.com, app.posthog.com. These domains appear on every major blocklist. The blocking is not sophisticated — it is simple domain matching, and it works.

Privacy-focused tools like Plausible and Fathom use lighter scripts, but their collection domains — plausible.io and cdn.usefathom.com — are explicitly listed in the EasyPrivacy filter list. uBlock Origin loads EasyPrivacy by default, meaning these tools are blocked for its 40+ million users. Browser-native protections in Brave and Firefox catch them as well.

The only architecture that passes every test is cookieless cookieless collection from a first-party domain. There is no third-party script for blockers to identify. The data collection happens on a domain that belongs to the website owner. From the browser's perspective, it is indistinguishable from a normal first-party request — because it is one.

The compound data loss

Ad blocker losses do not exist in isolation. They compound with consent rejection losses. Consider the math for a typical European website using a client-side analytics tool:

That means between 72% and 79% of your actual traffic is invisible. You are making budget decisions, attribution models, and campaign optimizations based on roughly one quarter of reality. The data loss is not a rounding error — it is a structural failure in measurement.

For tools blocked by all 5 ad blockers — GA4, Adobe Analytics, PostHog — the problem is even worse. Every visitor running any form of blocking is completely invisible.

How we tested

We combined two approaches: filter list analysis and browser verification.

• —Downloaded the default filter lists used by each blocker — EasyList, EasyPrivacy, uBlock filters, and Peter Lowe's ad server list
• —Searched each list for every analytics domain (e.g., google-analytics.com, plausible.io, cdn.usefathom.com)
• —Verified in-browser with each ad blocker installed on a fresh Chrome profile using default settings
• —Binary pass/fail per combination — does the analytics request reach its collection endpoint?
• —For browser-native blockers (Brave, Firefox ETP), we tested with built-in protection set to strict mode

The filter list approach is more reproducible than browser testing alone — anyone can download EasyPrivacy and search for plausible.io or cdn.usefathom.com to verify the results. SealMetrics has one rule in EasyPrivacy: ||sealmetrics.com^$third-party — which only triggers when loaded as a third-party resource. Since SealMetrics uses first-party CNAME collection, this rule does not apply.

The bottom line

Ad blockers are not an edge case. With 30% adoption across Europe and growing, they represent a structural gap in any analytics setup that relies on client-side JavaScript loaded from third-party domains. The tools most commonly used in enterprise — GA4 and Adobe Analytics — are blocked by every major ad blocker without exception.

Cookieless, first-party collection is the only architecture that survives all five blockers. See how SealMetrics collects data without client-side scripts or calculate how much traffic your current setup is missing.