App-ads.txt. : What It Means for the Apps Ecosystem?

It all began with ads.txt.

Ads.txt, or Authorized Digital Sellers, is an initiative by the IAB Technology Laboratory (Interactive Advertising Bureau) designed to increase transparency and prevent online ad fraud in programmatic advertising. Ads.txt is a text file that publishers can add to their website, specifying which companies or ad networks are authorised to sell their inventory. The ads.txt protocol was first launched in 2017; by the end of the year, 44% of publishers were using ads.txt.

Now, the protocol has been extended to the app ecosystem with the launch of app-ads.txt.

App-ads.txt in action

The app-ads.txt file can be used by app publishers to show which ad networks and sources have been authorized to sell their inventory. App publisher can do this by adding the apps-ads.txt file to their website, and linking their app store listing to their website. DSPs can check the apps-ads.txt listings on app publishers’ sites, and only support bids from authorized sources specified in the apps-ads.txt file.

What app-ads.txt means for publishers and advertisers?

Publishers who include the app-ads.txt file on their websites are helping to create a safer environment for both the advertisers and publishers in the programmatic advertising industry.

Advertisers and brands can easily identify legitimate inventory, and avoid purchasing unauthorized ad space.

As it is expected that many DSPs will choose to only buy from publishers with app-ads.txt, publishers that have adopted it will have an opportunity to generate more revenue from brand campaigns. Publishers that won’t adopt the app-ad.txt will miss the chance to earn revenue from those brands campaigns and will be removed from the DSPs pool of targeted media.

The overarching mission of the app-ads.txt protocol is preventing ad fraud on programmatic exchanges – and both publishers and advertisers will benefit.

Implementing app-ads.txt: Step by Step

In a few steps, app developers can implement the app-ads.txt protocol, ensuring their inventory is covered:

1. Link your app store listing to your website

Include the URL of your developer website in your app store listing. Advertising networks will use the address to verify the app-ads.txt file.

2. Contact all relevant ad sources

Request the app-ads.txt line from your advertising networks. According to the IAB, the structure follows this outline:

  • Ad source domain: for StartApp this value is
  • Publisher’s account ID: this is StartApp unique ID for each publisher. It can be found on the right upper menu of the portal.
  • Type of account/relationship: app-ads.txt file should only include providers who work directly with publisher, or third-party resellers who have a relationship with the publisher direct partner.  If the partner is direct, it needs to be listed as DIRECT. For third party resellers it should be listed as RESELLER.
  • Certification authority ID. This is the ad source TAG ID. for StartApp leave this empty.

Here’s an example for StartApp:, 1100000000, DIRECT

3. Publish and upload your app-ads.txt file

Create an app-ads.txt file using any text editor you chose (for example, Notepad) and include all the lines you received from your ad providers. Upload it to your domain website.

What now?

Part of the success of the ads.txt initiative is due to the fact that it was relatively quickly adopted by a critical mass of publishers. Following the indisputable positive effect of ads.txt on the online ad industry, it is now time to bring the same protection to the mobile app ad space. Implementing app-ads.txt is voluntary. However, it is highly recommended that all publishers and DSPs take on the app-ads.txt protocol as best practice. More information about the initiative is available on the IAB Tech Lab website.

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