Authorisation
ads.txt vs sellers.json: what each one tells a buyer.
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ads.txt and sellers.json are both public files, and they're often mentioned together. But they answer different questions, and neither one is enough on its own.
| ads.txt | sellers.json | |
|---|---|---|
| Published by | The publisher | The SSP or exchange |
| Lives on | The publisher's domain | The platform's domain |
| Answers | Who may sell my inventory? | Who is behind each seller account? |
| For apps and CTV | app-ads.txt | sellers.json |
What ads.txt proves
ads.txt is the publisher's own list of authorised sellers. If a seller account isn't on it, the publisher hasn't approved that seller, whatever the deal description says. It also says whether each seller is direct, meaning the publisher's own account, or an approved reseller.
What sellers.json proves
sellers.json is the platform's list of the accounts it pays. It turns an anonymous seller ID into a named business, and says whether that business is a publisher or an intermediary. Without it, a buyer can see that an account was authorised but not who it belongs to.
Why you need both
- ads.txt alone tells you an ID is allowed, not who it belongs to
- sellers.json alone tells you who an ID is, not whether the publisher approved it
- Together they show both sides of every supply path in a deal