See What Ad Blockers Block on Your Site
Paste a URL. We load it in a real browser running uBlock Origin and show you every analytics, advertising, and consent tag that didn't make it.
Measured, not estimated
What the scanner actually does
No modelling and no extrapolation from browser market share — this is the browser's own account of what happened on your page.
The scan launches a real Chromium browser with uBlock Origin installed and its default filter lists compiled, navigates to your URL the way a visitor would, and records every network request the extension refused.
Results are grouped by the tool a request belongs to, because a list of blocked hostnames is not something anyone can act on. Seeing cdn.cookielaw.org in a log is noise; seeing "OneTrust — blocked" is a finding.
Each tool is then sorted into one of two buckets, and the distinction matters because the two failures look identical in your reports while being completely different problems:
Blocked on the way in
The tool's own JavaScript never downloaded, so it never ran. Anything waiting on it — every tag gated behind a consent banner, for instance — stayed blocked too.
Blocked on the way out
The script loaded and ran normally, but the request carrying its data was dropped. The visit happened, the code executed, and the measurement simply never arrived.
Interpreting the output
How to read your results
A scan is evidence about one page at one moment. Three caveats worth holding onto.
This is a worst case, not an average. uBlock Origin with default lists blocks more than the median real visitor does. Firefox's default protection and Safari's ITP work differently — they mostly restrict the cookies behind a request rather than dropping the request itself, so the session is counted but a returning visitor is misattributed as new. The scan measures outright blocking, which is the more visible failure but not the only one.
It describes one page, at one moment. Tags that fire only at checkout, after a consent choice, or on a different template won't appear. Scanning a landing page and a conversion page usually tells you more than scanning either alone.
A clean result deserves a second look. Nothing blocked is good news only if your tags were there to be blocked. If a page carries no third-party analytics at all, it scans clean for a reason that isn't worth celebrating.
To size the loss across all your traffic rather than one page, compare your analytics sessions against CDN or server logs for the same period. The scan tells you what breaks; the log comparison tells you how often.
Sources: Backlinko — Ad Blocker Usage Statistics · Brave — Shields · WebKit — Intelligent Tracking Prevention · Mozilla — Enhanced Tracking Protection in Firefox
Next steps
What you can do about blocked tags
Blocking happens because the request goes to a hostname on a filter list. Serving the same files and calls from your own domain removes what the filter matches on.
Fix the inbound blocks first
A blocked loader takes everything downstream with it. A consent platform that never renders holds back every tag waiting on consent, so one fix here often restores several tools at once.
Then the outbound drops
These are narrower — the tool works, only its data is lost — but they are the ones most likely to go unnoticed, because nothing on the page appears broken.
Mind the load order
Any first-party recovery depends on its own script having loaded. Place it directly in the page head, before your tag manager and consent snippet, so it is running before anything it needs to rescue.
Re-scan afterwards
The same scan is the check. Tools that stop appearing in the results are the ones you have recovered.
Ad Blocker Scanner FAQ
How do I check if my analytics are blocked by ad blockers?
Paste your URL above. The scanner loads your page in a real Chromium browser with uBlock Origin installed and reports every request the blocker stopped, grouped by the tool it belongs to. It takes about 15 seconds and needs nothing installed on your site.
Which ad blocker does this test against?
uBlock Origin with its default filter lists (EasyList, EasyPrivacy, Peter Lowe's list and uBlock's own). It is the most widely used blocker on desktop and among the most aggressive, so treat the result as a worst case rather than an average visitor.
What is the difference between a blocked script and a blocked measurement call?
A blocked script never ran at all — the browser refused to download it, so nothing that depended on it executed either. A blocked measurement call means the script did run, but the request carrying its data was dropped on the way out. The first breaks the tool; the second silently loses the data while everything appears to work. The scan reports them separately because they fail differently and are fixed differently.
Why does the scan show my consent banner as blocked?
Consent platforms like OneTrust and Cookiebot load from third-party CDNs that appear on standard filter lists. When the loader is blocked the banner never renders, so every tag waiting on consent stays blocked too — one blocked request can account for all your missing analytics.
Does a clean scan mean ad blockers aren't costing me data?
Not necessarily. It means uBlock Origin blocked nothing on the page that was scanned. Tags that only load on other pages, after a consent choice, or during checkout would not appear. It is also worth confirming your tags are actually present — a page with no analytics at all scans clean for the wrong reason.
Can I scan a page that requires a login?
No. The scanner loads pages anonymously, exactly as a first-time visitor would, so anything behind authentication is out of reach. Scan the public equivalent — a landing page, product page, or your home page — since those carry the same tag configuration in most setups.
Related
Recover what's being blocked
Introtrace serves blocked scripts and re-sends dropped measurement calls through your own domain. Free to start with 20,000 recovered signals per month.