Sellers.json Checker

Exchanges covered

Lines pointing at any other exchange are reported as “not checked” rather than guessed at.

Questions

What is sellers.json?

Sellers.json is the buy-side half of the ads.txt system. Ads.txt is you declaring who may sell your inventory; sellers.json is each exchange publishing the sellers it actually works with. Buyers cross-reference the two. When your ads.txt claims a relationship the exchange does not confirm, that path can be treated as unauthorised.

Why would my seller ID be missing from sellers.json?

Usually one of four reasons: the ID was mistyped, the account was closed or merged, you copied a partner’s ID from a template file, or the exchange has not published the record yet. All four look identical to a buyer — an unverifiable path — so all four cost you bids.

What does a confidential seller mean?

Exchanges may mark a seller as confidential, which hides the name and domain while still confirming the ID exists. It is permitted by the spec and common, but some buyers apply lower bids to confidential paths because they cannot see who they are buying from.

What is a seller type mismatch?

Sellers.json labels each seller PUBLISHER, INTERMEDIARY or BOTH. If your ads.txt declares a line as DIRECT but the exchange lists that seller as INTERMEDIARY, the two disagree about whether you are the owner of the inventory. That contradiction is one of the clearest signals of a misconfigured or resold supply path.

Is my ads.txt file sent to your server?

No. Your file is parsed in your browser, and only the exchange domain and seller ID from each line are sent so they can be looked up. We never fetch a URL you supply — exchange domains are resolved against a fixed internal list, which is what keeps the endpoint from being usable as a proxy.