Inspect your authorized digital seller declarations.

Need to verify account declarations against a seller list? Use the sellers.json Checker with ads.txt joint validation.

Fetches /ads.txt over HTTPS on the exact host you enter. Use the root domain unless checking a declared subdomain. The target must allow browser access (CORS). No proxy is used.

Paste content, select a file, or fetch a domain to begin. Local content stays in your browser.

What this checker verifies

Checks the three required seller fields, optional certification ID, DIRECT / RESELLER relationships, comments, duplicate records, and ads.txt 1.1 declarations. Semicolon extension data is recognized but not validated. A certification ID is optional and is not required to be a specific length.

This is a syntax check, not an authorization or compliance certification. It does not verify DNS, public suffix boundaries, seller account ownership, sellers.json, certification IDs, country-code assignment, referred files, or redirect-chain compliance. HTTP metadata is checked only for fetched files. Empty files are not treated as proof that no sellers are authorized.

If fetching fails, open the file in a new tab and paste its contents here. A browser network or CORS error does not prove that ads.txt is missing.

IAB Tech Lab ads.txt specification