What is Sellers.json?

Sellers.json is an IAB Tech Lab standard. Ad exchanges and supply-side platforms (SSPs) publish a public JSON file that lists seller accounts on their platform. Each entry maps a seller ID to a legal business name, domain, and whether the party is a publisher, intermediary, or both. Buyers use it to confirm who is paid for a given impression and to spot mislabeled or unauthorized resale.

Table of Contents

  1. How does sellers.json work?
  2. Why does this matter for ad fraud and click fraud?

How does sellers.json work?

Publishers use ads.txt to say which exchanges may sell their inventory and which seller IDs apply. Sellers.json is the exchange-side mirror: hosted at a fixed path on the exchange domain (often the root sellers.json file), it turns an opaque seller ID into a real entity.

Typical fields include:

  • seller_id – matches the ID referenced in ads.txt and in bid traffic
  • name and domain – who gets paid
  • seller_type – PUBLISHER, INTERMEDIARY, or BOTH
  • is_confidential (optional) – when set, some details may be hidden; buyers often treat that as higher risk

During a programmatic auction, a demand-side platform can read the publisher’s ads.txt, then look up the seller ID in the exchange’s sellers.json. If the chain does not line up, the buyer can avoid bidding or apply stricter rules.

Why does this matter for ad fraud and click fraud?

Ad fraud often depends on hiding the true source of inventory or posing as a premium site. Sellers.json does not stop invalid clicks or bot traffic by itself, but it cuts down domain spoofing and mystery resellers by making seller identity checkable at scale.

For paid search and landing pages, the same idea applies indirectly: campaigns that sit next to programmatic buys benefit when your organization enforces clean supply paths. Stricter seller verification reduces budget flowing to misrepresented placements. Teams that care about lead quality often pair supply hygiene with junk lead controls and tools such as fraud detection that look at behavior, not only seller files.

Many advertisers also combine IAB transparency files with suspicious click monitoring and platform invalid-traffic filters for a fuller picture.

Frequently Asked Questions

  • Is sellers.json a replacement for ads.txt?

    No. ads.txt lives on the publisher domain and lists which exchanges and seller IDs may sell that inventory. sellers.json lives on the exchange domain and maps each seller ID to a legal name, domain, and seller type. Buyers normally read both so the declared seller in the bid chain matches a known entity. Together they reduce mystery resellers; neither file replaces the other.

  • Does a complete sellers.json file prove traffic is human?

    No. sellers.json confirms who is entitled to sell and get paid for an impression, not whether a real person generated it. Bot traffic, hidden iframes, and other invalid activity still require measurement filters, SSP controls, and advertiser rules. Combine supply transparency with behavior checks and context on bots and ad fraud.

  • Who maintains sellers.json?

    Each SSP or exchange publishes and updates its own file at a standard URL on its domain. Buyers, verification vendors, and auditors crawl or cache those files the same way they crawl ads.txt. If a seller entry is stale or marked confidential, treat the gap as a risk signal and tighten bidding rules until the chain is clear.

Abisola

Abisola

Meet Abisola! As the content manager at ClickPatrol, she’s the go-to expert on all things fake traffic. From bot clicks to ad fraud, Abisola knows how to spot, stop, and educate others about the sneaky tactics that inflate numbers but don’t bring real results.