The Ads.txt filter is a feature that can be used to restrict domains purchased through the platform to only come from sellers which are defined in the publisher’s Ads.txt file. Ads.txt stands for Authorized Digital Sellers and is a project that aims to create transparency in the programmatic advertising ecosystem. In the Ads.txt file, publishers can declare the authorized sellers for their inventory. Ensuring that domains can only be purchased through this list of sellers defined by the publisher, this increases protections against fraudulent inventory and authenticates that the URL passed in the ad call is an accurate representation of the inventory being bought and the seller it is coming from. You can see an example of an ads.txt file here: cnn.com/ads.txt

For more information on the Ads.txt project, visit the IAB website here: https://iabtechlab.com/ads-txt-about

To enable the Ads.txt feature, open the ‘Edit Targeting’ section of a Line Item. In the ‘Ads.txt’ tab, check the box, then ‘Save’ and submit the Line. This feature can only be applied to ‘Web’ inventory and will not affect targeting for Deal inventory or In-App inventory. The Ads.txt file is only applicable to domains sold through the Open Exchange.