Short answer: a tab-under is an ad trick where, when you click, the page opens a copy of itself in a new tab and sends your current tab to an ad. Because the new tab is on the same site, most pop-up blockers allow it. AdTabBlock stops the swap so your current tab stays where it was.
How a tab-under works
- You click something on the page: a video, a download button, or empty space.
- The page instantly opens itself again in a new tab. That tab looks like the page you were on.
- At the same moment, a script sends your current tab to an ad.
- You see the ad. The page you wanted is now sitting in a different tab, so it feels like the site "moved".
Pop-under vs tab-under
| Pop-under | Tab-under | |
|---|---|---|
| Where the ad appears | A new tab or window, often behind yours | Your current tab |
| Where your page goes | Stays put | Moves to a new tab |
| Why blockers miss it | It opens right after your click | The new tab is on the same site, and the ad loads in a tab that already existed |
Why most blockers miss it
Pop-up blockers look for new tabs going to other websites. In a tab-under, the new tab goes to the same site, so it looks harmless, and the ad loads in a tab that was already open. Some tab-blocking extensions even say plainly that ad redirects in the same tab still get through.
How AdTabBlock stops it
AdTabBlock watches for this exact pattern: a page opens a tab and then, within a moment and without you clicking a link, tries to send your current tab to another website. When it sees that, it cancels the swap. If a site manages to slip it through, AdTabBlock sends your tab back to the page you were on. Links you click yourself are never affected.
Keep your tab where it is. AdTabBlock stops tab-unders automatically.
Add to ChromeWant to see it? The third test on our test page is a safe tab-under. With AdTabBlock on, your tab stays on the test page.
Questions
What is a tab-under ad?
A tab-under is an ad trick where a page opens a copy of itself in a new tab and redirects your current tab to an ad, so the ad appears in the tab you were using.
How do I stop tab-under redirects in Chrome?
Chrome's built-in blocker doesn't stop them. AdTabBlock, a free Chrome extension, detects when a page opens a tab and then tries to send your current tab to another site, and cancels it.