In the previous part we’ve introduced a concept of fill rate – percentage of ad requests fulfilled with actual ads.

The harsh reality is that it’s almost never 100% for any particular commercial ad network – there’s just more ad space on the web and in apps (supply) than there’s advertising dollars to spend on that space (demand). Your ad network is basically doing the sales for you and as all the sales-based operations they may have better or worse months, stronger or weaker areas like countries and regions or industries.

Therefore while implementing an SDK from just one network into your app is very easy, as most of the money related things, it’s not that easy to get the maximum result out of those ads.

Ad mediation, waterfall, etc.

Some ad providers are doing what is often called server-side mediation. You integrate one SDK into your app and the ad server offers your users to multiple ad networks who bid on that ad request based on the desires of the advertisers they have. The whole auction happens in real-time hence the term you’ve probably heard before – real-time bidding or RTB.

This is all good, but it’s still limited to the number, quality and relevance of the ad networks integrated into your provider’s backend. It also ads additional uncertainty on the type of advertising you’ll get delivered to your users since it’s coming from any of the multiple sources that you don’t necessarily have any control of.

So instead of, or in addition to, using an ad mediation network you can do your own client-side mediation or what some call a waterfall algorithm.

What it means is that you integrate multiple ad provider SDKs into your app and switch between them based on your own criteria. In the simplest form you request an ad from your most preferred ad network and, if it can’t provide one, you switch to your number 2, etc. A more sophisticated solution would allow you to have different setup for each region and update your configuration without having to update your app.

You can build a simple system like this yourself or you can use a solution that someone else made. On the Windows side there’s an open-source project called AdRotator and then there’s Microsoft’s own Ad Mediation.

The last step

In a setup like this you have the most control of what’s going on in your app and with some experimentation you can get pretty close to that coveted 100% fill rate. There’s only one thing separating you from true 100% – something that, even if you can’t get paid for the impression, will provide an ad no matter what.

This could be an ad for your other apps or games, or an ad for your friend’s app, or an ad for your favorite charity. You can also swap ads with some other friendly publishers or join a cross-promotion network to promote your app for free and without sacrificing any potential revenue – remember that at this step you are using your unsold inventory which would go to waste otherwise.

Not only for fill rate

While these techniques would definitely help you improve the ad fill rate in your apps, you can take it one step further. Once you’ve achieved virtually 100% fill rate you can start optimizing the order of ad networks in your waterfall in different countries and different types of apps and games. This way you’ll be able to configure your setup in a way that yields you the best returns.

Whether this exercise is worth the trouble is for your to decide, but know that there’s always a room for improving your ad monetization. It won’t make a difference between starving and royal riches, but once you get to a certain level, even a few percent improvement could be pretty substantial in absolute numbers.