app-ads.txt for DSPs

Understand app-ads.txt

Publishers use the app-ads.txt file to designate authorized digital sellers of their ad inventory, DSPs use it to validate that they are buying inventory through an authorized source. Implementation is optional, but we strongly recommend it for the purpose of transparency.

In 2018, the IAB launched ads.txt, a file enabling web publishers to designate authorized digital sellers of their ad inventory. app-ads.txt is the mobile in-app equivalent of this specification, which mobile publishers can implement. This text file declares their Authorized Digital Seller (ADS) List to prevent unauthorized sellers from profiting off their inventory or from selling counterfeit inventory.

Implement app-ads.txt

  1. Identify app store listing URLs. MoPub passes the app store listing URL in the storeurl attribute of the app object in the bid request.

  2. Crawl app listing page in the app store. It is then up to the DSP to crawl app listing page in the app store to identify the app developer’s developer webpage.

  3. Translate the Developer URL into an app-ads.txt path as follows:

    • Extract the host name portion of the URL.
    • Remove all but the first (and, if present, second) name from the host name, which precedes the standard public suffix.
    • Remove any www. or m. prefix remaining in the host name. Crawlers should attempt to fetch the HTTPS version of the URL first, falling back to the HTTP version if SSL is unavailable.
  4. Crawl and interpret the app-ads.txt file.

While this spec is optional, we encourage all publishers and DSPs to adopt app-ads.txt as a best practice to help further our industry’s overall transparency and trust. For more information please visit the IAB Tech Lab’s specification in its entirety on its website.

Last updated August 28, 2021

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