sellers.json

A public file SSPs and exchanges host disclosing every seller ID they operate on behalf of.

sellers.json is the counterpart to app-ads.txt: every SSP or exchange hosts a file at a well-known URL listing each seller ID it uses, whether that seller is confidential, and the seller's name and domain when disclosed. Combined with app-ads.txt and the schain object, it lets a buyer verify that every hop in a bid's supply chain is a real, authorized, and named party.