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Last updated: January 15, 2024

About Sellers.Json

The IAB Tech Lab has introduced two new technical specifications aimed at increasing trust of the supply chain, specifically on the supply-side of real-time bidding and programmatic buying. The first, sellers.json, enables buyers to verify the entities who are either direct sellers of, or intermediaries in the selected digital advertising opportunity for purchase. The second, the OpenRTB SupplyChain object, allows buyers to see all parties who are selling or reselling a given bid request. The OpenRTB Working Group finalized the specifications for industry adoption on July 31, 2019.

Ads.txt (Authorized Digital Sellers) has been extremely successful in allowing publisher content distributors and app publishers to define who is authorized to sell a given set of impressions (publisher’s advertising inventory) via a bid request. Ads.txt does not however make any attempt at revealing the identities of the publisher account IDs within their advertising platform(s): Publisher’s SSP (Supply-Side Platform).

What Is Sellers.Json?

sellers.json provides a mechanism to enable buyers to discover who the entities are that are either direct sellers of or intermediaries in the selling of digital advertising.

A published and accessible sellers.json file allows the identity of the final seller of a bid request to be discovered (assuming that they are ads.txt authorized).  It also allows the identities of all nodes (entities that participated in the bid request) in the SupplyChain object to also be discovered. Currently, it is possible for the final seller to be identified via the and Publisher.domain attributes, but in practice, these properties are inconsistently populated by various selling systems. sellers.json enables smaller bid request object sizes by allowing this information to be looked up and cached “offline” rather than supplied with every bid request. sellers.json also allows the identification of any and all intermediaries that participated in the selling of a bid request.

What is the OpenRTB Supply Chain Object?

  1. The SupplyChain object enables buyers to see all parties who are selling or reselling a given bid request. This information can be important to buyers for any number of reasons including transparency of the supply chain, ensuring that all intermediaries are entities that the buyer wants to transact with and that inventory is purchased as directly as possible. The implementation should be as transparent as possible to buyers. It should enable them to easily understand who it is that is participating in the sale of any piece of inventory.

    The SupplyChain object is composed primarily of a set of nodes where each node represents a specific entity that participates in the selling of a bid request. The entire chain of nodes from beginning to end would represent all sellers who were paid for an individual bid request.

How Should an SSP Take Action?

The expectation is that SSPs and exchanges would post their sellers.json files for buyers to review. SSPs and exchanges would also upgrade their OpenRTB integrations (on versions 2.x or 3.0) to include support for the SupplyChain object (an OpenRTB extension). Combining all of these standards and components gives advertisers and agencies the tools to understand what they’re buying, empowering them to be more confident and comfortable in their purchases.

How Should DSP/Buyers Take Action?

Buyers should continue to target inventory sold through ads.txt and app-ads.txt channels, cutting out misrepresented inventory by buying through authorized channels.

Buyers can review SupplyChain object, and verify identifiers within sellers.json files. This supply path transparency should support more confident Programmatic spend.