What is App-Ads.txt?

App-ads.txt is an extension of the ads.txt standard specifically designed for mobile and connected TV (CTV) applications. Introduced in 2019, this specification addresses the unique challenges of in-app advertising fraud.

Unlike traditional ads.txt which relies on domain ownership, app-ads.txt accounts for the distributed nature of mobile apps where publishers don't control the app store URLs (like apps.apple.com or play.google.com). Instead, it creates a verifiable link between the app developer and their authorized sellers.

The Mobile Advertising Fraud Challenge

Mobile in-app advertising represents over 70% of total digital ad spend, making it an attractive target for fraudsters. App spoofing and bundle ID fraud cost advertisers billions annually, with sophisticated actors creating fake apps that impersonate popular titles to sell fraudulent inventory at premium rates. The closed nature of app stores initially made fraud detection more difficult than in the web environment, as advertisers couldn't simply visit a URL to verify an app's authenticity.

Industry Adoption and Revenue Impact

Major demand side platforms have responded by requiring app ads.txt for access to premium inventory. This shift has created a bifurcated market: developers with proper app ads.txt implementation see improved eCPMs of 20 to 40 percent as sophisticated buyers prioritize verified inventory, while those without face reduced demand and lower fill rates. The standard has become a prerequisite for serious app monetization, particularly for developers seeking to work with tier one advertisers.

How App-Ads.txt Works

The app-ads.txt mechanism creates a chain of verification that bridges the gap between app stores and ad exchanges. Understanding this tri-part relationship helps developers appreciate both the elegance and complexity of the solution.

The Three-Component Verification Chain

App-ads.txt verification begins with the app store listing. Each major app store (App Store Connect, Google Play Console, etc.) allows developers to specify a developer website URL in their app metadata. This URL creates the crucial link between the app's bundle ID (which appears in ad requests) and the developer's web infrastructure. When a bid request arrives claiming to represent a specific app, verification platforms first retrieve the developer website URL from the app store listing.

The second component is the developer's website, which must host an app-ads.txt file at its root directory. This file follows the same basic format as regular ads.txt but applies to mobile app inventory. Crucially, the app-ads.txt file does not contain bundle IDs—the connection is made through the app store metadata rather than within the file itself. This design choice acknowledges that developers may publish multiple apps while maintaining a single developer website.

During real-time bidding, demand-side platforms execute a multi-step verification process. When receiving a bid request for app inventory, they extract the bundle ID, query the appropriate app store API to retrieve the developer website URL, fetch the app-ads.txt file from that website, and verify that the seller making the bid request is authorized. If any link in this chain breaks—if the app store listing lacks a developer URL, if the website doesn't host an app-ads.txt file, or if the seller isn't listed—the bid request can be rejected or devalued.

Implementation Steps

Developer Website Configuration

Begin by establishing a publicly accessible website under your control. This website will host your app ads.txt file and serves as the trust anchor for all your applications. The site must use HTTPS, as many verification platforms reject insecure connections. Importantly, this need not be a dedicated domain for app ads.txt alone. Many developers use their existing corporate website or developer portal. The critical requirement is consistency: the URL specified in your app store listings must exactly match the domain hosting your app ads.txt file.

App Store Metadata Updates

Each app store provides a field for developer website URLs within app metadata. For iOS applications, navigate to App Store Connect, select your app, and update the Developer Website field under App Information. Android developers should access Google Play Console and specify the website URL in the Store Listing section under Store Presence. Connected TV platforms each have their own developer consoles with similar fields. Verify that these URLs point to domains where you can host files, as some developers mistakenly list URLs they cannot control, such as social media profiles or app store pages.

File Creation and Authorization Management

Contact each advertising partner currently monetizing your applications. Request complete app ads.txt entries from their account managers rather than constructing entries manually. Each partner will provide their canonical domain and your unique publisher identifier. Unlike standard ads.txt files, app ads.txt files do not contain bundle IDs. The verification chain links bundle IDs to your developer website through app store metadata, then from your website to authorized sellers through the app ads.txt file. This indirection allows a single file to authorize sellers across multiple applications under the same developer account.

Deployment and Verification

Upload the completed file to your website root directory, ensuring accessibility at yourdomain.com/app ads.txt. Test manually by visiting the URL in a browser and confirming that the plaintext content displays correctly. Use automated validation services like ads txt.ai to verify proper HTTP configuration, syntax correctness, and successful integration with app store listings. Many implementations fail because the file is placed in a subdirectory, served with incorrect content type headers, or the app store listing still references an outdated URL.

Platform-Specific Considerations

Common Implementation Mistakes