sellers.json
sellers.json is a public file that exchanges and SSPs publish to reveal the sellers and intermediaries authorized to sell inventory through them.
sellers.json is a public file that an ad exchange or Supply-Side Platform publishes to disclose every seller and intermediary authorized to sell or resell inventory through it. Created by the IAB Tech Lab, it is the seller-side complement to ads.txt: where ads.txt is hosted by publishers, sellers.json is hosted by the platforms.
How it works#
The file lists each seller account ID along with the seller's name, domain, and type, marked as PUBLISHER, INTERMEDIARY, or BOTH. A buyer who sees a seller ID in a bid request can look it up in the exchange's sellers.json to learn exactly which company that ID represents. Some sellers are listed as confidential, but the structure still confirms an authorized relationship exists.
Why it matters#
sellers.json lets buyers trace a bid back to the real entity profiting from each impression, exposing chains of resold inventory and demand partners that would otherwise be opaque. Combined with the SupplyChain Object (schain), which records the ordered path of intermediaries in a given bid request, it gives buyers end-to-end visibility into who touched an impression and took a margin. This transparency is central to detecting fraud, eliminating unauthorized resellers, and running effective supply path optimization.
Related terms: ads.txt, SupplyChain Object (schain), and Resold Inventory / Demand Partner.
