To help build a safe and transparent advertising ecosystem, we’re introducing support for app-ads.txt across Google AdMob and Google Ad Manager. This will help app publishers prevent their inventory from being spoofed by bad actors while ensuring advertiser spend reaches the intended audience. 

What is app-ads.txt?

App-ads.txt is a standard released by the IAB Tech Lab that helps prevent unauthorized or domain-spoofed app inventory from being transacted across mobile, connected TV, and other devices. It defines a simple method for app publishers to publicly declare who is authorized to sell or resell their digital advertising inventory. App-ads.txt is an extension of the original ads.txt standard that was first published by the IAB in 2017. The ads.txt standard is one of the most successful industry standards and is now widely adopted by web publishers. 

Google’s support for IAB Tech Lab’s app-ads.txt

We’ve actively contributed to the specification of app-ads.txt since the beginning and will support the standard across all relevant products including AdMob and Ad Manager. Starting August 27, 2019, we will begin to block ad serving of unauthorized app inventory in both AdMob and Ad Manager as identified by a publisher’s app-ads.txt file. 

We strongly encourage you to create an app-ads.txt file and publish it to the developer domain you have listed in your App Store and/or Google Play store listing. This will help prevent unauthorized and domain-spoofed app inventory from damaging your brand and revenue.  Publishers who do not implement an app-ads.txt file will see no changes to their ad serving, but they will not benefit from these added spoofing protections.

How to prepare for the enforcement  

Correct implementation of app-ads.txt will help protect your inventory against bad actors. Implementation errors could cause interruptions to ad serving, so it is very important for you to verify that the app-ads.txt file you publish on your developer domain contains all your valid property codes before August 27. 

To prepare for the upcoming enforcement rollout, simply follow the steps below. You can find more details in our Help Center guides (AdMob, Ad Manager). 

1. Provide a developer website URL in app store listings on Google Play or the App Store
2. Publish an app-ads.txt file in the root directory of your site (e.g. example.com/app-ads.txt)
3. Include all authorized publisher codes for the networks your app sells through in the file

Once you finish implementing the app-ads.txt file, we encourage you to carefully review it to ensure that it contains lines in the following format: 

google.com, pub-0000000000000000, DIRECT

As the sample line shows, your app-ads.txt file should include the name of the ad network you are working with (e.g. ‘google.com’) as the domain name and you should replace the publisher ID with your property code. 

To help you verify correct file implementation, we are currently rolling out verifications and warnings in the user interface for both AdMob and Ad Manager when errors are detected. The warnings will appear if we detect your publisher ID is missing from your app-ads.txt file.

There will be no interruption to your ad serving should you choose not to implement the app-ads.txt file on your developer website, but your app may be at risk of inventory spoofing which could result in revenue loss. 

By supporting the new app-ads.txt standard, AdMob and Ad Manager will help you better protect your revenue and brand.