Implement and validate an ads.txt file to declare a publisher's Authorized Digital Sellers per the current IAB Tech Lab spec
domain: iabtechlab.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Publish a plain-text /ads.txt file at the root domain (and subdomains as needed) listing each authorized seller as a comma-delimited record
Adopt Ads.txt 1.1 fields where relevant — OWNERDOMAIN and MANAGERDOMAIN — to declare ownership/management relationships introduced in the August 2022 spec update
Verify the file is reachable over HTTP/HTTPS at the standard relative path from every domain that serves the publisher's inventory
Cross-check declared seller IDs against each SSP's sellers.json file for consistency
Re-crawl and re-validate the file periodically, since ads.txt is a living declaration that changes as seller relationships change
Known gotchas
ads.txt has iterated through several versions (1.0 in 2017 through 1.1 in 2022, adding fields like SUBDOMAIN, CONTACT, INVENTORYDOMAIN, OWNERDOMAIN/MANAGERDOMAIN) — confirm which fields a given crawler or buyer actually supports before relying on the newest ones
ads.txt only covers web inventory; apps need the separate app-ads.txt file at the developer's website, not the app store listing
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