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. Create the app-ads.txt file in Notepad.

    If you have multiple frontend accounts (publisher IDs), make sure that your app-ads.txt file reflects this. Create a row for each publisher ID in the app-ads.txt file.

    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.

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

  4. Validate that the file is taking effect. While we do not currently offer a validator tool for app-ads.txt, you can verify that it is correctly implemented by appending “/app-ads.txt” to your main domain (as in, https://<>/app-ads.txt).

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.

Integrate with Rubicon

Additionally, MoPub has an integration with Rubicon’s trusted exchange. With this integration, you immediately gain access to a larger number of DSPs through the MoPub Marketplace, with additional brand-focused spending at high CPM. To access this high-value demand, include the following entry in your app-ads.txt file:, 21648, RESELLER, 0bfd66d529a55807

Last updated August 24, 2020

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