Digital MarketingGlossary
Paid Media

Ads.txt

advertising standard

01 Definition

Ads.txt meaning: A public file publishers post to declare which companies may sell their ad inventory.

Ads.txt is an IAB Tech Lab standard file placed at a site's root that lists the sellers and resellers authorized to offer its inventory. Buyers check it to confirm they are purchasing from legitimate sources, which curbs domain spoofing and unauthorized reselling. It verifies authorization, not the quality or value of the inventory.

Also called

authorized digital sellers

Why it matters

How Ads.txt fits the work

Ads.txt lets buyers confirm they are dealing with authorized sellers, reducing spoofed inventory and helping legitimate publishers keep control of how their supply is sold.

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In context

Before buying, the platform checked the publisher's ads.txt file and confirmed the exchange offering the inventory was listed as an authorized seller.

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Practical note

Ads.txt only confirms who is allowed to sell inventory; it does not prove impressions are viewable, fraud-free, or worth the price you pay for them.