app-ads.txt for Publishers

Understand app-ads.txt

Publishers use the app-ads.txt file to designate authorized digital sellers of their ad inventory, and 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 your Authorized Digital Seller (ADS) List to prevent unauthorized sellers from profiting off your inventory or from selling counterfeit inventory.

Implement app-ads.txt

To implement app-ads.txt:

  1. Provide a developer website in your app store listings. Ensure that the proper developer website URL is accessible in the developer website section of the app store.

  2. Publish an app-ads.txt file. Create this document in Notepad, and include the following data:

    • Ad Source Domain: For MoPub, this value is

    • Publisher ID: Refer to these instructions to find your Publisher ID.

    • Type of Relationship: All of MoPub’s publisher relationships are direct, so the value for MoPub is always designated as direct.

    • Ad Source ID: This is the ad source’s TAG ID. For MoPub, the value is 74b46c0ea83967ca.

    • Publish the app-ads.txt file in the root of the app developer’s developer website; for example,

Here is an example of the MoPub entry in a publisher’s app-ads.txt file. The four parameters are separated by commas, with a separate line for each authorized partner:, [pub id], DIRECT, 74b46c0ea83967ca

Although implementing 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, refer to the IAB Tech Lab’s specification in its entirety on its website.

Last updated November 05, 2019

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