The undetectable ad blocker

How websites detect ad blockers

Anti-adblock systems plant decoy ad elements and check whether they get hidden, fire test requests to ad servers and check whether they're blocked, and probe for ad-related JavaScript globals. A normal blocker reacts to all of these in a way the page can measure.

Once detected, the site can hide its content behind a wall, show a nag, or quietly degrade your experience. You blocked the ads, but the site knows — and fights back.

What makes a blocker undetectable

Being undetectable means passing those probes as if no blocker were present: the decoy element looks visible, the test requests look answered, the expected globals exist. AdOff operates in the page's main execution context and spoofs the bait elements, intercepts detection fetches, and masks the variables anti-adblock relies on.

The result: ads are removed at the network and cosmetic level, but the probes come back normal. No wall, no nag.

Test your current setup

You can check whether your current ad blocker is detectable with our free, private in-browser test — it runs the same probes anti-adblock scripts use and shows the result in five seconds.

→ Test if your ad blocker is detectable

Frequently asked questions

Can websites tell if I'm using an ad blocker?

Usually yes. Most blockers leave measurable traces. A stealth ad blocker like AdOff spoofs those signals so detection scripts see nothing unusual.

How do I make my ad blocker undetectable?

Use a blocker with a dedicated stealth layer that runs in the page context and masks bait elements, test requests, and detection variables. AdOff includes this in its Pro and trial tiers.

Is an undetectable ad blocker against the rules?

Blocking ads is your choice on your own device. AdOff simply blocks ads without leaving the traces that trigger anti-adblock walls.