Sellers.JSON and the OpenRTB SupplyChain object

Roy Cohen


September 17, 2019
1 Comment

The IAB Tech Lab recently introduced two new technical specs for public comment: Sellers.JSON, and the OpenRTB SupplyChain object.
These initiatives aim to increase Brand Safety, Transparency, and enhance trust between partners within the AdTech ecosystem.

The object specifications for Sellers.JSON and the OpenRTB SupplyChain were introduced in order to resolve the gap that was created by Ads.txt and App-Ads.txt, which help to determine who is authorized to buy the inventory but still does not cover the different hoops or intermediaries that may participate in the inventory reselling process.

Sellers.json and SupplyChain are mechanisms used to identify all intermediaries that participate in the money flow all the way from the buying platform back to the publisher.
They does not include any intermediary that does not participate in money flow and doesn’t include systems that are paid a fee for their services, but don’t pay upstream sellers. In cases of complicated supply chains, this enables increased transparency and the ability to identify and prevent fraudulent or otherwise unacceptable supply sources, according to the business policies of the consuming advertising system (SSP’s/DSP’s).

Both initiatives can be thought to be some sort of extension to the Ads.txt initiative, introduced back in 2017. Nevertheless, they were introduced in order to resolve the gap created by Ads.txt and App-Ads.txt which helps to determine who is authorized to buy the inventory but still do not covers the hoops or intermediaries that participate in the reselling process.

Sellers.JSON is the Ads.txt file of the SSP’s, Exchanges or any Ad Network that participate in reselling the ad space.
AdServers, Exchanges, Ad Networks and SSP’s need generate the Sellers.JSON file on their root domain (for example:, and it should include the account ID’s of all the customers that operate under this vendor. It should list all the Publishers, Ad Networks and any other SSP’s that generate supply for this specific Advertising System.

OpenRTB SupplyChain Object
The SupplyChain object is the de facto solution for buyers to see all parties involved in the reselling of a given ad space opportunity by chaining each node from the publisher back to the DSP.
Each node in the chain includes the following information:

  1. asi – The canonical domain name of the SSP, Exchange, Header Wrapper, etc. system that bidders connect to. This may be the operational domain of the system, if that is different than the parent corporate domain, to facilitate WHOIS and reverse IP lookups to establish clear ownership of the delegate system. This should be the same value as used to identify sellers in an Ads.txt file if one exists.
  2. sid – The identifier associated with the seller or reseller account within the Advertising System. This must contain the same value used in transactions (i.e. OpenRTB bid requests) in the field specified by the SSP/exchange. Typically, in OpenRTB, this is For OpenDirect it is typically the publisher’s organization ID. Lastly, it should be limited to 64 characters in length.
  3. hp – Indicates whether this node will be involved in the flow of payment for the inventory. When set to 1, the Advertising System in the asi field pays the seller in the sid field, who is responsible for paying the previous node in the chain. When set to 0, this node is not involved in the flow of payment for the inventory. For version 1.0 of SupplyChain, this property should always be 1. It is explicitly required to be included as it is expected that future versions of the specification will introduce non-payment handling nodes. Implementers should ensure that they support this field and propagate it onward when constructing SupplyChain objects in bid requests sent to a downstream Advertising System.

With this additional transparency of the supply chain, buyers can determine the specific opportunity is clean and can verify all the intermediaries. Buyers will now have the ability to understand how much “hands” their bid is passed through and, in turn, they can decide to cut some intermediaries in order to provide better performance as well as to minimize their spend and maximize their enrichment.

Aniview's Adserver's approach to Sellers.JSON and the OpenRTB SupplyChain object:
Aniview is a leading Ad Server that helps its customers comply with the Sellers.JSON and the OpenRTB SupplyChain object.
Aniview can also help you manage your entire Supply.JSON file and close the loop of your Ads.txt.
All our integrations support the SupplyChain object, whether it is through OpenRTB, VAST or PreBid.

For more information, please reach out to your dedicated Client Success Manager.

Aniview's SSP's approach to Sellers.JSON and the OpenRTB SupplyChain object:
As an SSP, already supports the Sellers.JSON and SupplyChain object with all of their demand partners with 100% coverage.


Stay Updated

Subscribe to our newsletter to stay connected
with industry news and professional tips