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isblocked.fyiIs your tracking data quietly disappearing?
See which adblockers block your analytics, ads and tags, and get told when it changes.
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Adblockers decide what your tracking can see
Analytics tags, ad pixels and tagging endpoints are filtered by browsers and extensions before they load. When a domain lands on a filter list, data disappears from your reports with no error and no alert. isblocked.fyi shows who blocks what, and tells you when that changes.
Search any domain
See if uBlock Origin, Brave, AdGuard, AdBlock Plus, Safari and more block any tracking, analytics or tag-manager domain.
Discover what is blocked
Browse blocked hosts by category, from analytics to server-side tagging, ranked by how many websites load them.
Get told when it changes
Monitor a domain or pattern. Get an email or webhook when a list adds or removes it, before your reports show a gap.
How much of your data goes missing
Around a third of internet users run a blocker, and the default lists in uBlock Origin, Brave, AdGuard and Ghostery cover the big analytics and ad domains. Built-in protection in Brave, Firefox and Safari adds to that, with no extension installed. The more technical your audience, the bigger the gap.
1.1 billion
people use an ad blocker, about 30% of all internet users
448 million on desktop, 629 million on mobile. Mobile is the growing side (eyeo, Q4 2025).
1 in 3
US internet users block ads. Worldwide it is 29.5%
Share of internet users aged 16 to 64 who block ads at least sometimes (GWI, Q2 2025).
58%
of visitors from Hacker News and Reddit never reached Google Analytics
Measured on one tech-heavy site by comparing it to a first-party proxy that blockers cannot see (Plausible, 2021).
Analytics traffic that blockers typically hide
Share of visitors, by type of business
- Developer tools and SaaS40 to 60%
- B2B software30 to 50%
- Gaming and entertainment25 to 40%
- Finance and fintech25 to 35%
- News and media20 to 35%
- E-commerce15 to 25%
- Food and lifestyleunder 10%
Ranges are directional estimates, not measurements, and your own audience will differ. Sources: eyeo 2026 Ad-Blocking Report, GWI via Backlinko, Plausible Analytics, Introtrace. To see what is blocked on your own site, run the website checker below.
Website checker
Which of your tags would an adblocker stop?
Enter your website. We load it, record every resource it requests, and check each one against the same index, blocker by blocker.
- Every host the page talks to, not just the main tags
- Blocked by default versus only with optional lists
- Free: one scan a day, more with an account
Used by
Agencies that monitor their clients' tracking setups with isblocked.fyi
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Frequently asked questions
Which adblockers does isblocked.fyi cover?
The most used ones: uBlock Origin, Brave, AdGuard, AdBlock Plus, Ghostery, Firefox, Microsoft Edge, DuckDuckGo and Safari. For each one we track the filter lists it uses, so you see what its users actually get.
What is the difference between blocked by default and optional lists?
Blocked by default means a blocker stops the domain out of the box, with nothing for the user to do. Optional means it only stops it when the user turns on an extra filter list. Default blocking affects everyone who uses that blocker.
Why would my analytics or ad tags get blocked?
Tracking and ad domains end up on filter lists such as EasyPrivacy. Visitors whose blocker uses those lists never load your scripts, so pixels stop firing and your reports lose data, with no error and no alert.
How does the website checker work?
Enter your website and we load it, record every request it makes, and check each one against the major adblockers. You get the hosts and URLs that would be blocked, and by which blocker. A scan takes about 20 seconds. You get one a day for free, and more with an account.
Can I search for a path like /collect, or use a regex?
Yes. Besides full domains you can search for paths and URLs, use * as a wildcard, or turn on the regex button to match patterns such as ^metrics\..+\.com$. This finds tracking endpoints that live on a path, not only on a domain of their own.
How do I get told when something changes?
Sign in and add a domain, a path or a pattern to monitor. We check the lists every day, and when a matching entry is added or removed you get an email or a webhook, before the gap shows up in your reports.
How fresh is the data, and does it match what my visitors have?
We re-fetch and compare all the lists once a day. Blockers can differ from their defaults, because users change settings or add their own lists, so treat the results as what a typical user with default settings would get.