Ad Mediation
Ad mediation is a technology layer that manages multiple ad networks and runs real-time auctions to fill each impression with the highest bid.
Definition
Ad mediation is software used by app publishers to maximize revenue from in-app advertising by connecting to multiple ad networks at once and automatically serving the highest-paying ad for each impression. Instead of integrating one ad network and accepting whatever eCPM it offers, a publisher using mediation lets multiple networks compete for each impression in real time.
Modern mediation platforms use in-app bidding (also called header bidding for mobile), where all connected networks bid simultaneously in a real-time auction for each impression opportunity. The highest bidder wins and their ad is served. This replaced the older 'waterfall' model, where networks were ranked in a fixed priority order and called sequentially until one filled the impression, which was slower and left revenue on the table.
The major mediation platforms are AppLovin MAX, ironSource (now Unity LevelPlay), Google AdMob, and Mintegral. They each connect to dozens of demand sources including Meta Audience Network, Google, Unity Ads, and hundreds of smaller networks, all competing for publisher inventory.
Why it matters
For app publishers monetizing through ads, mediation directly determines how much revenue each impression generates. Without mediation, you're leaving money on the table every time a lower-paying network serves an ad that a higher-paying network would have bid more for. Publishers using in-app bidding via mediation typically see 15 to 30% higher eCPM than those using fixed waterfall setups. For UA teams, understanding mediation matters because it affects the inventory dynamics on networks you buy on.
Example
In practice
A casual game integrates AppLovin MAX mediation with 8 connected ad networks. For a rewarded video placement, Meta bids $18 eCPM, Unity bids $14, and AppLovin Exchange bids $21. MAX serves the AppLovin Exchange ad, earning the publisher the highest available rate for that impression.
Frequently asked questions
What's the difference between ad mediation and programmatic advertising?
Programmatic advertising is the automated buying and selling of ad inventory. Ad mediation is a specific tool publishers use to manage programmatic demand from multiple networks simultaneously. Mediation sits on the supply side (publisher); programmatic DSPs sit on the demand side (advertiser). They're complementary parts of the same ecosystem.
Do I need ad mediation if I only use one ad network?
If you're only using one network, mediation adds no value. But connecting even two or three networks through mediation typically increases eCPM meaningfully because competition between networks drives up bids. Most serious mobile publishers use mediation from the point they have meaningful ad revenue.