sellers.json
A transparency file published by ad tech intermediaries listing all publishers they represent.
What is sellers.json?
sellers.json is a transparency standard published by the IAB Tech Lab that complements ads.txt. While ads.txt is hosted by publishers to declare authorized sellers, sellers.json is hosted by ad tech intermediaries (SSPs, exchanges, ad networks) to declare all the publishers and resellers they represent. Together, these two files create a verifiable chain of authorization from publisher to advertiser.
The sellers.json file is hosted at the root domain of the ad tech company (e.g., google.com/sellers.json) and lists every seller account on their platform along with the seller's name, domain, and whether they are a publisher (direct seller) or intermediary (reseller).
Why It Matters for Publishers
sellers.json affects publishers because advertisers and DSPs use it to verify the legitimacy of inventory sources. If your SSP's sellers.json doesn't properly list your account as a publisher, DSPs may flag your inventory as potentially fraudulent or unverified, resulting in lower bid rates and CPMs.
The combination of ads.txt and sellers.json creates a full transparency chain: advertisers can verify that the SSP offering inventory is listed in the publisher's ads.txt, and that the publisher is listed in the SSP's sellers.json. Breaks in this chain reduce buyer confidence and bid volume.
Best Practices
- Verify your listings: Check each of your SSPs' sellers.json files to ensure your publisher account is listed correctly with accurate domain and name information.
- Choose transparent partners: Work with SSPs and exchanges that publish comprehensive, up-to-date sellers.json files. Non-transparent intermediaries receive less demand from quality-conscious advertisers.
- Request confidentiality if needed: sellers.json supports confidential entries where your specific identity is not publicly disclosed, useful for publishers who prefer privacy while still maintaining verification.
- Monitor the full chain: Periodically trace the authorization chain from your ads.txt through your SSPs' sellers.json to ensure there are no breaks that could be limiting your demand.