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What is sellers.json and schain object

What is sellers.json?

Sellers.json, together with the SupplyChain Object, is the latest specification released by IAB Tech Lab in April 2019. In a nutshell, it helps advertisers check on the stage of the bid request and whether the specific reseller has permission for the publisher’s inventory distribution within the advertising chain.

How does sellers.json & Supply Chain Object work?

  • Sellers.json has similar functions as ads.txt. However, a JSON format is applicable instead of .txt. It is also placed in the root of the supply-side platform (SSP) or Ad Exchange domain, and it is publicly available. The mechanism allows listing authorized ad tech vendors in partnership with an SSP.
  • SupplyChain Object is the second specification working along with sellers.json. This mechanism runs on the demand-side platform and helps buyers to watch so-called ”nodes”, which determine every active reseller during the bid request. All vendors are automatically checked with parties’ IDs listed in ads.txt placed on the publisher’s side. Hence, the buyer/ advertiser may verify if vendors are in a partnership with the original seller.
  • Sellers.json and SupplyChain objects are compatible with the Open Real-Time Bidding versions 2.5 and 3.0. Ad tech vendors are responsible for hosting the files.


Sellers.json file is the json file that consists of the following components:

  • seller_id
  • name
  • domain
  • seller_type


Sellers.json Example


SupplyChain object

SupplyChain object reporting is required to capture the supply partners’ IDs in bid requests and establish visibility into the path from the inventory source to the buyer. It happens after they combine ads.txt and sellers.json data to a specific bid request. 

When implemented correctly, SupplyChain Object data can provide a more thorough understanding of the programmatic transactions. For example, a user can check sellers.json and ads.txt files to find out and get validation of an inventory source. In addition, SupplyChain Object can reveal that the bidding request is passing through many resellers. Therefore, when together with ads.txt and sellers.json, ad exchanges or DSPs can easily ensure the validity of the sellers in the supply path, and there is a possibility for double confirmation of authorized sellers, a chance to detect an incomplete chain, on top of the direct inventory that SupplyChain Object users also get. Ultimately, this is a mutually beneficial solution for identifying and eliminating the poor-quality supply that works for all parties involved in the supply chain and improving bid transparency. 


SupplyChain object is the object in RTB bid requests that consists of the following components:

  • asi
  • sid
  • rid
  • hp



To find out more details regarding sellers.json and supply chain object,  proceed to our blog