What does an ads.txt file do?

ads.txt (Authorized Digital Sellers) is an initiative developed by the Interactive Advertising Bureau (IAB) to combat ad fraud and unauthorized inventory sales in programmatic advertising. It's a simple text file that publishers place on their web servers to declare the companies authorized to sell their digital ad inventory.

Here's how ads.txt files work:

  1. Publisher Identification: Publishers create a list of authorized digital sellers (ad networks, exchanges, or SSPs) that are authorized to sell their ad inventory. They specify this information in the ads.txt file.
  2. File Placement: The ads.txt file is placed in the root directory of the publisher's website. It's publicly accessible and can be accessed by anyone.
  3. Syntax: Each line in the ads.txt file contains information about a specific seller. The information includes the domain name of the advertising system, the publisher's account ID, and the relationship between the publisher and the advertising system.
  4. Crawling and Verification: Ad buyers and ad platforms crawl the ads.txt files of publisher websites they want to buy ad space from. They use this information to verify which sellers are authorized to sell the publisher's ad inventory.
  5. Fraud Prevention: ads.txt helps prevent unauthorized sellers from misrepresenting ad inventory. If an ad exchange or SSP is not listed in the publisher's ads.txt file, buyers can avoid purchasing inventory from them, reducing the risk of ad fraud.
  6. Transparency and Accountability: ads.txt promotes transparency in the digital advertising ecosystem by providing a mechanism for buyers to verify the legitimacy of sellers. It also holds publishers and ad platforms more accountable for the ad inventory they sell.

Overall, ads.txt files play a crucial role in promoting transparency, reducing ad fraud, and increasing trust in programmatic advertising transactions.