Publishers offering "Interstitial Ad" spots

An interstitial ad fills the whole screen between two pages or app screens, usually at a natural pause such as a level change or a page transition. Mobile sizes like 320x480 and 360x640 are common, and Liftoff and Moovit run them inside apps.

How it's sold: You book it through an app network or ad platform, often programmatically, or ask the publisher's sales team for a direct slot. Three of the six publishers sell it on the web and three in apps.
What it costs: Most publishers quote it on request, and it is usually priced per 1,000 impressions or per install on app networks.
What you supply: You supply a full-screen image, HTML5 or video creative at the sizes the publisher lists, plus a clear close-friendly end card and a landing link.
Best for: It suits app installs and strong one-message awareness bursts.
Before you buy: Check how often one person sees it and whether the publisher caps frequency, because repeat full-screen ads annoy people quickly.