The file links an account identifier to the company selling through it. ads.txt supplies the authorization from the publisher’s side; sellers.json supplies identity information from the ad system’s side. (Google sellers.json guidance ↗ · IAB Tech Lab sellers.json specification)
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Matching the seller account
Illustrative marketplace example: a publisher authorizes seller-42 for exchange.example in ads.txt. The same ad system’s sellers.json identifies seller-42 as an intermediary and lists reseller.example as the business domain of the company paid under that account. The publisher investigates whether the account and resale relationship match its agreement; it does not reject the entry just because the intermediary’s company domain differs from the publication’s domain. These are example fields, not a claim about every marketplace’s file.
When a different domain is expected
A different company domain can be expected when an authorized intermediary sells the inventory. An unknown account or unexplained company is a reason to ask the partner for the relationship, not a reason to delete every record whose domain differs from your publication.
How to compare the two files
Start with the advertising system and seller account listed in ads.txt. Look up that same account in the system’s sellers.json file. Compare the role and business identity the seller represents. A matching name without a matching account does not settle the question.