Ad Blocker Detector
See the exact technique sites use to detect your ad blocker — without being nagged by it.
How this test works
A small element is inserted with class names drawn from common filter lists — the kind of markup an advertisement would carry — and after a moment its dimensions and computed style are checked. If something removed or hid it, a filter is running. That is the whole mechanism behind every “please disable your ad blocker” overlay you have seen: plant bait, measure it, change the page if it vanished. This page performs the first two steps and deliberately not the third. It is also worth knowing how weak the signal is: blockers vary in whether they touch bait elements at all, and one configured to allow this site produces exactly the same result as no blocker.
What the results mean
- Decoy element
- The bait. Hidden or removed means something is filtering the page.
- Page changed by this result
- No, by design. The technique is being demonstrated rather than applied.
- Reliability
- Low. False negatives are easy and common.
- Blocking
- Something filtered the bait. It does not identify which blocker or what else it filters.
Common problems and fixes
- I have a blocker but it says not blocking
- Your blocker may allowlist this site, or simply not target the bait markup. Both produce a negative, which is why the reliability is described as low.
- It says blocking but I have no extension
- Some browsers filter by default, and network-level blocking on a router or DNS service produces the same result.
- Will this page nag me?
- No. The result is reported and nothing else happens.
Frequently asked questions
How do sites detect ad blockers?
Mostly like this: insert an element with markup that filter lists target, then check whether it survived. Some also check whether a known ad script loaded. Both are easy to defeat and easy to false-positive.
Does this site use ads?
Yes, which is stated plainly because a page testing for ad blockers has an obvious interest in the answer. The result does not change anything you see.
Can I be detected even with a good blocker?
Sometimes, and the arms race continues in both directions. But detection is far less reliable than the confident overlays suggest.