Supply path optimization (SPO)

Supply path optimization (SPO) is the practice of selecting the most efficient and transparent paths through which to acquire ad inventory. In programmatic buying, the same impression can reach a buyer through different sellers and resellers; SPO is about choosing among those routes.

ads.txt: who is authorized to sell. IAB Tech Lab's ads.txt (Authorized Digital Sellers) lets publishers and app publishers declare who is authorized to sell their inventory. It is an anti-fraud tool aimed at domain misrepresentation, and app-ads.txt extends it to apps distributed through mobile and connected-TV app stores. On its own, ads.txt does not reveal the identities behind the publisher account IDs it lists.

sellers.json: who the sellers are. sellers.json lets buyers discover the entities that are either direct sellers of, or intermediaries in, the sale of digital advertising. SSPs and exchanges are expected to publish these files for buyers to review.

The SupplyChain object: every hop in a bid request. The OpenRTB SupplyChain object lets buyers see all parties selling or reselling a given bid request. It is a chain of nodes, each representing one entity that took part — from beginning to end, all the sellers who were paid for that request. IAB Tech Lab says this can help buyers ensure intermediaries are ones they want to deal with and that inventory is purchased as directly as possible.

Putting them together. The OpenRTB Working Group finalized sellers.json and the SupplyChain object for industry adoption on July 31, 2019. IAB Tech Lab's guidance is for buyers to keep targeting inventory sold through ads.txt-authorized channels, review the SupplyChain object and verify identifiers in sellers.json files.