Fight fraud and improve eCPMs: How to implement app-ads.txt for your app

The IAB Tech Lab created the app-ads.txt framework to ensure app inventory is sold through authorized channels, safeguard against fraud and streamline supply chain management. This gives developers more control over who’s allowed to sell ads on their apps and buyers the ability to validate more inventory as an authentic supply source — paving the way to increased revenue for both.

By creating an app-ads.txt file and keeping it updated regularly, you’re taking a critical step towards preventing ad revenue loss through ad spoofing and other malicious activities.

What is it?

Originally developed for web sites, ads.txt combats various types of ad fraud — such as domain spoofing and illegal inventory arbitrage. It also ensures transparency in the market. App-ads.txt is an extension to the ads.txt standard for mobile apps. 

42 Matters reports that app-ads.txt is more commonly adopted among the top apps in the app store than overall apps – setting a new standard of transparency and security in the mobile advertising ecosystem. 

• For the Google Play Store, 68.7% of the top 1,000 Google Play apps implemented app-ads.txt.
• For the Apple App Store, 42.4% of the top 1,000 Apple App Store apps implemented app-ads.txt. 

How does it work?

App-ads.txt files are publicly accessible and can be crawled by exchanges, supply-side platforms (SSP), other buyers, and third-party vendors. Developers host these files on the root domain of their website, which is linked from the Google Play Store or Apple App Store. All ad sources authorized to sell the developer’s inventory are listed in app-ads.txt, which is cross-referenced with IAB’s system for buyers to identify authorized sellers.

Advertisers can verify that the developer ID included in the ad request matches the corresponding ID in the app-ads.txt file when sending an ad request for an app. They can do this by visiting the app store page for the app and finding the corresponding app-ads.txt file.

This ID verification prevents malicious actors from faking ad requests under the guise of an app because the developer ID in their ad request will not match the developer ID included in the app-ads.txt file. You can read more about it from the Interactive Advertising Bureau here. 

What are the benefits?

• Mitigates ad fraud. App-ads.txt blocks developers attempting to impersonate legitimate apps and mislead brands into spending on fake inventory.
• Reduces risk of being blacklisted. More advertisers now rely on app-ads.txt adoption to ensure they buy authorized inventory. Adopting app-ads.txt helps developers avoid blacklisting.
• Improves revenue. With fraud instances reduced, authenticated developers can retain more of the ad revenue from inventory genuinely targeted to their app.

How can I implement it?

1. Add your developer website to the app store. A developer website lets your users learn more about your apps and other content. It’s also how the app-ads.txt standard establishes who owns an app. You must link your developer website in your store listings in Google Play or the App Store so AppLovin and other ad platforms can establish your app’s ownership.
2. Create your app-ads.txt file. Post the app-ads.txt file on the root folder of your developer website, listing all authorized sellers of their app inventory. Reach out to the ad networks implemented in your app(s) and ask for the relevant lines you should add to the file.
   
   Note: Make sure to format your file according to the IAB Tech Lab standard in order to be verified. If you need additional help, review the Authorized Sellers for Apps specification provided by the IAB Tech Lab.

How can I add AppLovin to my app-ads.txt?

1. In MAX, go to the app-ads.txt info page to find the AppLovin entry to add to your and add your app-ads.txt file.
2. From the MAX main menu, go to Account > Basic Info. In the Domain field, add the root domain of your developer website URL where the app-ads.txt file lives — for example, mywebsite.com.

What are the best practices?

• Use a service to host app-ads.txt for you if you don’t have your own website.
• List your developer website URL on all the app stores distributing your app. 
• Make sure the developer root domain is present in MAX.
• Use a tool such as Ads.txt Guru to validate your app-ads.txt. 

With MAX, AppLovin is committed to hosting a safe and transparent app marketplace. We encourage all our developers to adopt app-ads.txt to improve revenue — and it’s important that both ad networks and developers do their part to reduce fraud. To learn more, check out our documentation here. If you have any questions, please reach out to your account team or submit a support ticket.