Ad Mediation

Ad mediation is a technique that lets app developers manage multiple ad networks through a single SDK. Instead of integrating each network separately, developers route every ad request through one layer, where networks compete to fill the placement. That competition raises eCPMs and ad revenue.

Ad mediation platforms help app publishers manage multiple ad networks on one centralized platform, which streamlines reporting and optimization. Without it, publishers need to manage each ad network through their individual SDKs and platforms. Ad mediation platforms help publishers sell more inventory and increase fill rates by making each ad network bid against each other. The publishers accept the highest bid, reaching optimal fill rates, and effectively increase eCPMs.

The core problem ad mediation solves: Eight networks means eight SDKs, eight dashboards, eight sets of rules. You’re stuck checking stale data, tweaking priorities that are already out of date, and scrambling every time an SDK update drops. This isn’t just slow — it’s broken. You miss impressions, make decisions on old data, and burn engineering time on maintenance instead of building your product. Mediation wipes all that out. One system, automated, always optimizing.

How Ad Mediation Works: Step by Step

The mobile app calls the ad mediation platform via the SDK, indicating that a session started and will be requesting an ad. The platform identifies which ad network is eligible to show the ad then organises a sequence of ad networks.

The mediation SDK in the app sends one bid request to every connected network in parallel. Each network returns a bid price plus a creative. The highest valid bid wins. The mediation SDK serves the creative and logs the impression. Three filters run before a bid can win: format and size match; floor price (a bid below the publisher’s per-country, per-format floor is dropped); brand safety and frequency caps.

Waterfall Bidding vs. In-App Bidding

There are two main architectures in ad mediation:

Waterfall Bidding (Legacy)

Traditional waterfall bidding ranks ad networks based on historical data, such as fill rates and eCPM. With each ad request, the top-ranked network gets the first chance to fill it. If that network can’t fill the request (or doesn’t meet the floor price), the request “falls” down to the next network in line. This continues until the ad slot is filled or the waterfall is exhausted.

The limitation: network rankings are based on historical averages, not real-time bids. A lower-ranked network might be willing to pay more for a specific impression, but it never gets the chance.

In-App Bidding (Current Standard)

In-app header bidding uses programmatic technology to have multiple advertisers bid in real-time for a certain ad space, where the highest bidder wins.

In-app bidding is what header bidding did for the open web, applied to mobile. AppLovin MAX moved fully to bidding in 2020. Unity LevelPlay and AdMob both default new apps to bidding-first stacks in 2026.

In-app bidding consistently outperforms waterfall on eCPM and fill rate. Public benchmarks from AppLovin and Unity show eCPM lifts of 15 to 40 percent when an app moves from a single network or waterfall to in-app bidding mediation with 6+ networks.

Key Metrics in Ad Mediation

eCPM (Effective Cost Per Mille): Revenue earned per 1,000 ad impressions. The primary metric for evaluating ad mediation performance. Higher eCPM = more revenue per impression.

Fill Rate: The percentage of ad requests that are successfully filled with an ad. Higher fill rates mean that a larger portion of your ad space generates revenue. A 95% fill rate means 5% of ad requests go unfilled and earn nothing.

ARPDAU (Average Revenue Per Daily Active User): The revenue generated per user per day. Fill rate and eCPM together determine ARPDAU.

Ad mediation boosts app/site ad revenue by creating competition among ad networks via a single SDK. It targets improvement of fill rate and eCPM — the two main drivers of ad revenue.

Leading Ad Mediation Platforms in 2026

Four platforms control most of the in-app mediation market.

AppLovin MAX: The most widely adopted mediation platform in 2026. Supports in-app bidding with AppLovin’s AXON ML system optimizing bid selection. Free to use — AppLovin makes money through its own ad network.

Google AdMob Mediation: Native integration with Google’s ad ecosystem. AdMob bidding ML optimizes demand. Defaults new apps to bidding-first in 2026.

Unity LevelPlay (formerly ironSource): Unity bought ironSource in 2022. Strong for game developers already in the Unity ecosystem. Supports both waterfall and bidding.

Most apps in 2026 run AppLovin MAX plus AdMob as their primary mediation pair, with additional demand sources integrated through each platform’s network connections.

Privacy Considerations for Ad Mediation in 2026

SKAdNetwork 4 and Privacy Sandbox shape the auction. iOS 14.5+ stripped IDFA from most users. Android Privacy Sandbox is rolling out to select users in 2025 and 2026. Mediation platforms now route deterministic and probabilistic signals through the bid request to keep CPMs from collapsing.

The deprecation of device-level advertising identifiers — Apple’s IDFA and Google’s GAID — changes how ad mediation works at the attribution and targeting layer. Mediation platforms have adapted by supporting on-device signal processing and contextual targeting methods that don’t rely on individual user identifiers.

When Should an App Use Ad Mediation?

Almost always, for apps with meaningful ad inventory. Some platforms can perform up to 20% better than single-network approaches. The setup cost — one SDK integration — is a one-time investment that pays back quickly in improved fill rates and eCPMs.

For a new app, the practical move in 2026 is simple: ship with one mediation SDK. Wire 6 to 10 in-app bidders. Watch eCPM, fill rate, and ARPDAU together.