Ad Fraud

Sellers.json: An IAB Tech to Improve Programmatic Transparency

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After the massive adoption of ads.txt, IAB is ready with another tech release to combat ad fraud in the digital supply chain. On April 11th, IAB Tech Lab launched two new standards—sellers.json and OpenRTB Supply Chain Object. IAB believes lack of transparency leads to ad fraud like domain spoofing where attackers impersonate publishers. With sellers.json, IAB wants to make the supply chain transparent and safe for everyone involved.

What is Sellers.json?

Sellers.json is a relatively new tech introduced by IAB that lets supply-side partners keep a list of inventory providers (programmatic publishers and resellers); in comparison, ads.txt is where publishers keep a list of authorized sellers.

Basically, with sellers.json, SSPs and ad exchanges declare the publishers and inventory providers they are partnered with and whose inventory they have the permission to sell. SSPs and ad exchanges host this file on their servers and are responsible for managing it. To check sellers.json list of a partner, simply type their domain followed by ‘/sellers.json’. For example: appnexus.com/sellers.json.

sellers.json example

And What is OpenRTB Supply Chain Object?

Supply Chain complements the use of sellers.json. It enables buyers to see all the parties selling/reselling a specific bid request. It is composed of a set of nodes, where each node represents a seller in the supply chain. Basically, it gives a pathway to understand the flow of bid requests from the website to the advertiser’s ad creative.

Source: IAB GitHub

Sellers.json and OpenRTB Supply Chain Object come in as a single package. Demand-side uses both the technologies to track bid requests and empower transparent, confident purchases.

What Does Sellers.json Include?

Object: Parent

The Parent object is the top-level object that acts as a container for all properties in a sellers.json file.

AttributeTypeDescription
sellersrequiredA list of all sellers
versionrequiredThe version of sellers.json spec, currently the only valid value is 1.0
identifiersoptionalAn ID to identify the host of sellers.json (example – TAG-ID)
contact_emailoptionalEmail to contact the host
contact_addressoptionalBusiness address of the host
extoptionalAny specific extension to above details

Sellers.json object: Identifier

Although identifier is an optional field, it allows sellers to communicate values such as business identifiers, certification identifiers, or any other identifier that a consuming system might need to better interoperate with the seller.

Attribute TypeDescription
namerequiredDescription of identifier
valuerequiredValue of identifier

Sellers.json object: Seller

A final list of all publishers and resellers that have partnered up with the host.

AttributeTypeDescription
seller_idrequiredA unique identification number for each seller; same as the one mentioned in the ads.txt. This is a required field to identify the publisher or seller
seller_typerequiredAn inventory seller can be ‘PUBLISHER’ seller (like publisher—owner of site/app), ‘INTERMEDIARY’ (doesn’t own site but authorized to sell a part of it) or ‘BOTH’
is_confidentialoptional, default 0Identity of seller is confidential or not. 0 for not confidential and 1 for confidential
namerequired when is_confidential=0Name of the seller or publisher (example: Google AdExchange)
domainrequired  if seller has a webpresence and is_confidential=0Domain owned by seller under seller_id (example: google.com)
commentoptionalAny description or comment for the seller. For example, seller only allows native ads for available ad units
extoptionalAny specific extension to above details

How is Sellers.json Different from Ads.txt?

sellers.json and ads.txt

Both sellers.json and ads.txt are proposed by IAB aiming to bring more transparency to the supply chain. So what’s the difference?

  • Ads.txt is hosted by publishers and it contains the names of the authorized sellers for their inventories. On the contrary, sellers.json is hosted by SSPs and ad exchanges and contains a list of partner publishers and resellers.
  • Ads.txt is a simple text file. Sellers.json is written in JavaScript Object Notation format (JSON).
  • Both sellers.json and ads.txt help buyers to keep track of inventory origin. Although, sellers.json comes with OpenRTB Supply Chain Object, a road map of the entire supply chain for a bid; which is not the case with ads.txt

Why Does Adtech Need Sellers.json?

Most of the time, advertisers and demand-side do not deal directly with the publishers. Instead, ad exchanges and SSPs connect buyers to the inventory. In such a case, advertisers need inputs from SSPs or ad exchanges to get inventory details.

Next, given that it’s already a tedious job to manage the ad creative, decide their budget, and work on ad targeting, demand-side doesn’t really want to put the time to evaluate each of the bid requests received. Not to mention, it is difficult for advertisers to map bid requests to the website. With sellers.json, getting this information directly from SSPs or ad exchanges can save advertisers some time.

Finally, publishers don’t always directly sell their inventories. The supply chain is a series of networks and resellers, some of which do not get included in the ads.txt file. Basically, publishers don’t always know who is selling and reselling their impressions. Here too, sellers.json can help, as sellers will now keep a copy of the inventory they are dealing with.

What Else?

For the time being, the implementation of sellers.json and OpenRTB Supply Chain Object is not a mandatory measure. It is one of the good practices that brings back trust to the ad industry. If it reaches the critical mass, we will be able to see sellers.json to efficiently eliminate ad fraud.

With Google supporting sellers.json, the adoption of tech is expected to go up. With that hope the use of sellers.json is supported well, so that IAB’s efforts to curb ad fraud by bringing transparency would become successful.


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