sellers.json Validator
Validate any ad exchange or SSP's sellers.json file for IAB Tech Lab compliance. Check seller entries, identify missing fields, and verify supply chain transparency.
Enter an ad exchange or SSP domain to validate their sellers.json file. Try: google.com, openx.com, pubmatic.com, appnexus.com
What is sellers.json?
sellers.json is an IAB Tech Lab standard that brings transparency to the programmatic supply chain. Ad exchanges and SSPs host this file at their domain root to declare every authorized seller in their marketplace — whether that seller is a direct publisher or an intermediary reseller.
Together with the SupplyChain (schain) object that travels with each bid request, sellers.json lets buyers trace the full path of an impression from the original publisher to the final exchange. This transparency helps eliminate fraud, reduce arbitrage, and build buyer confidence in your inventory.
ads.txt vs sellers.json
ads.txt (publisher-side)
Hosted by publishers. Lists which exchanges/SSPs are authorized to sell their inventory. Says: "These platforms can sell my ads."
sellers.json (exchange-side)
Hosted by exchanges/SSPs. Lists which publishers and resellers are authorized sellers. Says: "These sellers are in our marketplace."
Together they form a two-way verification system. A buyer can check the publisher's ads.txt to confirm the exchange is authorized, then check the exchange's sellers.json to confirm the publisher is listed.
Frequently asked questions
What is sellers.json?
sellers.json is a file hosted by ad exchanges and SSPs at their domain root (e.g., exchange.com/sellers.json) that lists all authorized sellers in their marketplace. It enables buyers to verify who is selling inventory — whether as a direct publisher or an intermediary reseller. Together with the SupplyChain (schain) object, it creates full supply chain transparency.
How is sellers.json different from ads.txt?
ads.txt is hosted by publishers and lists which exchanges/SSPs are authorized to sell their inventory. sellers.json is hosted by exchanges/SSPs and lists which publishers and resellers are authorized to sell through them. Together they form a two-way verification: ads.txt says 'these platforms can sell my inventory' while sellers.json says 'these sellers are in our marketplace.'
Why does sellers.json matter for publishers?
When your exchange partner has a valid sellers.json that lists you as an authorized seller, DSPs and advertisers can verify your inventory is legitimate. This builds buyer confidence, reduces bid filtering, and can directly increase the CPMs you receive. Missing or incorrect sellers.json entries can cause buyers to filter out your inventory.
What fields are required in sellers.json?
Per the IAB Tech Lab specification, each seller entry must include: seller_id (unique identifier), seller_type (PUBLISHER, INTERMEDIARY, or BOTH), and is_confidential (boolean). Optional but recommended fields include: name, domain, and comment. The file must also include a contact_email and version at the top level.
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