What is ads.txt?

Ads.txt (Authorized Ditial Sellers) lets publishers declare who can sell ads on their website. IAB Tech Lab introduced the initiative to fight against fraud and misrepresented domains (spoofed domains).

How does it work?

A publisher places an ads.txt file containing all of the information about the programmatic partners they work with and hosts it on their web server under the root domain.

Here’s an example:, 12345, DIRECT, abcd123 – The platform the publisher uses to sell their inventory, e.g.

12345 – Seller Account ID. This is used to verify the authenticity of the inventory during real-time bidding auctions (RTB).

DIRECT – This field can either be DIRECT or RESELLER. It means either the publisher works directly with the vendor to sell the inventory or it means the publisher has authorized another company to sell inventory on its behalf, e.g. a digital advertising agency.

abcd123 – This is optional. It lists the Certification Authority ID, such as the Trustworthy Accountability Group (TAG).

View Thirdpresence Ads.txt