Popunder
A popunder is an ad format where a new window opens behind the currently active tab, so the user notices it later — when closing or minimizing the main window — rather than at the moment of the click. It's one of the oldest paid traffic formats in arbitrage, known for low CPM and high available volume.
How a popunder works
A click on almost any element on the placement, not necessarily an ad itself, opens a second window behind the current one without interrupting whatever the user was originally doing. That delayed contact is what separates a popunder from a popup, which covers the screen immediately at the moment of the click.
Popunders in PWA arbitrage
Low CPM and high available volume make popunders a convenient way to test new geos and offers on a modest budget, but the audience on average is less primed than push traffic — the user didn't consciously choose this transition. Because contact with the ad is delayed and often unexpected, instant PWA load time matters even more: a user who's just noticed a surprise window won't wait through a long preloader animation.
FAQ
- Why is popunder traffic usually cheaper than push?
- Because the available inventory on donor sites tends to be larger, and contact with the ad itself is less deliberate than opting into push. The lower price offsets the lower average traffic quality.
- Which verticals tend to perform best on popunder?
- Traditionally, verticals with a low decision threshold — casino, dating, and some nutra offers — where the user decides fast without needing a long warm-up. Verticals with a longer or more complex funnel tend to perform worse on this format.
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