While ads.txt has become a successful and widely supported initiative in the online advertising industry, it was just a part of a larger global effort to mitigate advertising fraud.

Aiming to keep the momentum going and achieve higher transparency and trust across the online advertising ecosystem, last year IAB Tech Lab introduced three more technical specs – app-ads.txt, sellers.json and OpenRTB SupplyChain object.

In this respect, while the implementation of app-ads.txt is solely an app publisher’s responsibility, the latter two come within the SSP’s/ad network’s purview.

What is Sellers.json?

In brief, seller.json is a file that maps out a list of publisher entities and associated account IDs operating on an SSP’s ad domain. This enables buyers to verify the final seller of a particular bid request, considering a seller is authorized in a publisher’s ads.txt.

What is OpenRTB SupplyChain Object?

Working in tandem with sellers.json, the OpenRTB Supply Chain object enlists all entities involved in the transaction of the ad impression as a set of nodes. This helps verify all intermediaries involved in the sale of the bid request.

Benefits of Sellers.json & SupplyChain Object

The industry-wide adoption of Sellers.json/SupplyChain object provides oversight and increases transparency of the entire supply chain, hence can help fight ad fraud more efficiently and enhance confidence across the digital ad ecosystem.

Keys to Sellers.json Implementation

Advertising platforms on the sell side post their sellers.json files into the root folder of their ad domain, following the same format as ads.txt, i.e. example.com/sellers.json. Please note that this URL is an example, hence visiting it will yield no result.

The file may include up to seven fields, yet only two of them are required. The other five fields are aimed at providing more context to the ad seller’s identity.

Namely, the required fields include:

  • “seller_id” – the identifier associated with the seller’s account within the ad system (the same ID that’s included in the ads.txt);
  • “directness” – represents the seller’s account type, which can be DIRECT (a website/app publisher), RESELLER (authorized reseller of the website/app ad inventory), or BOTH.

As for the optional fields in the sellers.json file, the widely used ones include:

  • “name” – represents the name of the entity (company), who will receive the payment for transacted ad inventory under the defined seller’s ID;
  • “domain” – the domain name of the entity (company), who will receive the payment for transacted ad inventory under the defined seller’s ID;
  • “is_confidential” – indicates the inventory seller’s identity is confidential.

Possible Downsides of Sellers.json

One of the possible gaps of sellers.json is an inventory vendor’s ability to label their account confidential, hence mask who they are. Whereas there might be legitimate reasons to use this option (e.g. in case the company’s offering whitelabel solutions), it still implies a potential blockage in the supply chain transparency. 

Another visible downside involves video ad management platforms, serving as proxies for small and mid-sized niche publishers. Even though these might actually be the only accessible source of the publisher’s ad inventory, they need to be defined as a “RESELLER” in the sellers.json file, which often is a less preferable option for buyers. Not only can it take a toll on the ad platform’s revenue, but also reduce monetization opportunities for many quality publishers on the market.

To peruse the specifications for sellers.json and the SupplyChain object in more detail, please visit the IAB Tech Lab’s website.