To ensure that your app ad inventory is only sold through channels you’ve identified as authorized, the Authorized Sellers for Apps (app-ads.txt) file comes in handy. It gives you more control over who’s allowed to sell ads on your app and helps prevent counterfeit inventory from being presented to advertisers. Implementing the app-ads.txt file helps prevent a significant loss in ad revenue.

Get started by updating your app's listing in the app stores (Google Play and App Store for Apple) to include your website in the developer contact URL. Be aware that you don’t need to list your full app-ads.txt URL in the app store listing as AdMob will crawl your website looking for this file using the domain portion of your website’s URL.

1. Sign in to your AdMob account, and create your app-ads.txt file by following the instructions by Google.

2. Once your file is ready, copy its code.

3. Then, open your website's integrations settings, find the Google AdMob field, and paste the code there:

4. Save the changes and update your website.

It can take up to 24 hours for AdMob to crawl and verify your app-ads.txt files.