Ads.txt (Authorized Digital Sellers) is an IAB Tech Lab standard that lets you publicly declare which companies are authorized to sell or resell your ad inventory. It's a plain text file, named ads.txt, hosted at the root of your website domain (for example, yourdomain.com/ads.txt). Each line in the file identifies one authorized selling partner.
App-ads.txt is the same standard extended to in-app and CTV inventory. Instead of living on the website where ads appear, the app-ads.txt file is hosted at the root of the developer domain listed in your app store listing. Buyers use your store listing to find that domain, then crawl the file to verify authorization for your app bundles.
Why ads.txt and app-ads.txt matter for your revenue
The IAB Tech Lab introduced ads.txt in 2017 to combat domain spoofing and inventory arbitrage—fraud schemes where bad actors sell inventory they don't own. To allow Sovrn to process bid requests and bid on your inventory, you must include Sovrn's required ads.txt or app-ads.txt lines on your domain or developer domain. Missing or outdated lines reduce eligible demand and can also impact your ability to be approved and onboarded through Sovrn's exchange.
How ads.txt and app-ads.txt work in the auction
Your ads.txt or app-ads.txt file is a public declaration of your authorized sellers. Advertisers and DSPs regularly crawl and catalog these files. When a DSP receives a bid request for your inventory, it checks that the seller and account ID in the request match an entry in your file. If they match, the request is treated as authorized and eligible for bidding. If they don't, the request is considered invalid and the DSP won't bid.
Because your file lists your account IDs with each selling partner, a fraudster copying your file gains nothing — buyers only pay the account ID declared in the file, which removes the financial incentive to spoof your domain or app.
Where to find your Sovrn ads.txt lines
Your account-specific ads.txt lines are available in the Sovrn Platform under Advertising > Ads.txt. Sovrn recommends keeping your live file in sync with the lines shown there. You will find three separate sets of ads.txt/app-ads.txt - one for web, one for app, and one for CTV. Be sure to select the right format before including your lines in your ads.txt file.
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