Definition
The term combines "pop" (a new window that pops) and "under" (it opens beneath the active window). Unlike a banner or a native placement, a popunder does not sit inside the publisher's layout; the entire landing page of the advertiser loads in the background tab. Because the visitor has just clicked on the publisher page, browsers treat the new tab as user-initiated and allow it, which is why the format survived the popup blockers that arrived with Internet Explorer 6 and Firefox 1.0 in 2004.
How a popunder works
- A publisher adds the network's script to a page.
- The visitor clicks on the page: a link, a video, an image.
- The script opens a new tab with the advertiser URL and returns focus to the publisher page.
- The network records an impression and charges the advertiser its CPM bid divided by 1,000.
- Frequency capping, commonly one popunder per visitor per 24 hours, prevents repeat delivery to the same person.
There is no creative to design. The advertiser's landing page is the ad, which is why the format is often the first one a new media buyer tests: the only variables are the landing page, the targeting and the bid.
Popunder vs popup
A popup opens in front of the current page and interrupts it; a popunder opens behind it and is seen later. Popups are blocked by default in modern browsers, so the pop format sold today is almost entirely popunder. On mobile devices the distinction blurs: the new tab opens behind the current one in the same way, but the visitor sees it the moment they switch tabs or close the publisher page.
How popunders are priced
Popunders are the cheapest format per impression because the advertiser supplies no creative and the publisher gives up no layout space. Prices are set per GEO and device: a bid for tier-3 traffic is a small fraction of a bid for United States iOS traffic. Networks publish a minimum bid per GEO and run a second-price or first-price auction above it. Some, Reacheffect included, also sell SmartCPM, where the platform lowers the bid to just above the next competitor, and SmartCPA, where the buyer sets a target cost per conversion and the platform adjusts bids toward it.
Who uses popunders
Advertisers with a landing page that converts on its own: iGaming and sports betting sign-ups, VPN and utility installs, sweepstakes and dating offers, and mobile subscription services. Publishers with high page-view volume and low display fill (streaming, file sharing, converters and tools) use popunders to monetize traffic that display ads price poorly, because one popunder per visitor per day earns more than a banner the visitor never looks at.
Related terms
| Term | Relation | Where defined |
|---|---|---|
| Pop traffic | Parent category | Term page |
| CPM | How popunders are priced | Term page |
| In-page push | Alternative format for the same offers | Term page |
| Frequency capping | Delivery control | Glossary entry |
FAQ
Are popunder ads legal?
Yes. Popunders are a standard, browser-permitted format when they are triggered by a user click and delivered with frequency caps. Networks enforce publisher policies on where the script may run and pre-moderate the landing pages advertisers send traffic to.
Do popunders work on mobile?
Yes. On mobile the new tab opens behind the current one in the same way, and mobile inventory is the majority of pop volume in most GEOs.
What is a good CPM for popunder traffic?
It depends on the GEO and the device. Tier-3 GEOs clear at a fraction of tier-1 prices. Current minimum bids by GEO and device are listed on the traffic-volume page with the date of the snapshot.