Sellers.json and Ads.txt File | Main Differences Explained

#Ad Fraud
sellers.json guide

Sellers.json file was introduced in 2019 by the IAB Tech Lab, following another important industry initiative–ads.txt, which rolled out in 2017. 

Both files–ads.txt and sellers.json–have the same goal: to provide more transparency about buyers, sellers, and resellers of the programmatic transactions and prevent ad fraud.

This article covers key features of sellers.json, the difference between sellers.json and ads.txt file, and benefits for publishers and advertisers. 

Table of Contents: 

What are the Differences Between Sellers.json and Ads.txt?

Ads.txt file allows publishers to define who is authorized to sell their ad inventory. Sellers.json provides advertisers with a mechanism to discover all parties (e.g., SSPs) involved in selling the publisher’s ad inventory. That includes intermediaries that don’t have a direct relationship with the publisher.  


What is Ads.txt?

Ads.txt is a publicly available file designed to prevent ad fraud. This file gives publishers greater control, as it allows them to declare sellers that are authorized to sell their ad inventory.

What is Sellers.json? 

Sellers.json is a file that contains the list of all authorized sellers and resellers of the publisher’s ad inventory, for example, SSPs or a monetization platform like Setupad.

Essentially, sellers.json is the next step after ads.txt to increase the transparency of the programmatic supply chain. 

Let’s picture a coin. For a long while, only one side of the coin was visible–the publishers’ side (ads.txt). Now, with sellers.json, you can see the other side as well—the sellers’ side (SSPs, intermediaries, and ad exchanges). 

How Does Sellers.json Work?

Sellers.json file works as an identification card of all legal entities participating in the programmatic auction, including publishers’ and intermediaries’ identities, their names, domain names, and seller IDs. 

Sellers.json Example

sellers json example

The sellers.json file consists of the following fields:

  • seller_id
  • seller_type
  • is_confidential
  • name
  • domain
what is sellers json

What is OpenRTB?

OpenRTB is a default method of buying and selling programmatic ads through a real-time auction. In OpenRTB, hundreds of advertisers bid on the publishers’ ad inventory simultaneously.

The process takes less than a second and allows displaying ads to users based on geolocation, demographic, or behavioral attributes. 

What is SupplyChain Object?

SupplyChain Object, also known as schain, is a part of an OpenRTB bid request. The object consists of nodes that represent all sellers (SSPs and ad exchanges) who were paid for an individual bid request.

It’s useful for advertisers because they can identify the final reseller in a bid request and verify if he is really authorized to sell that publisher’s ad inventory.  

sellers.json vs ads.txt
Source: Google

SupplyChain Object Example

Imagine that you are a publisher creating quality content. You chose Setupad as your monetization partner to access top-notch header bidding wrapper technology and increase your ad revenue

Setupad sells your ad inventory through one of our partner SSPs, for example, OpenX. While the advertisers bid on ad impressions in real-time, the SupplyChain Object collects information about OpenX and Setupad.

The advertiser who won in the real-time bidding auction can then check the sellers.json file of OpenX to see if Setupad was the authorized seller of the publisher’s ad inventory.

sellers json file

Where do I put my sellers.json?

You don’t need to worry about hosting the sellers.json file if you are a publisher. This is the responsibility of website monetization partners and ad exchanges, who need to add sellers.json files to their root domain and list all publishers or companies they work with.

What are the Benefits of Sellers.json?

Sellers.json is more relevant for advertisers. Nevertheless, the adoption of this file is beneficial for both publishers and advertisers. 

  • Increased Transparency: Both publishers and advertisers have greater confidence in a transparent marketplace where all parties are identified. 
  • Reduced Ad Fraud: Sellers.json helps advertisers quickly spot fraudsters by revealing who is authorized to sell publishers’ ad inventory.
  • Increased Ad Spend: By decreasing ad fraud losses, advertisers spend more money on ad spaces.
  • Trust: Advertisers have an easy mechanism to verify the publishers’ identity, which helps to build long-term relationships.


The fight to prevent ad fraud is in the programmatic advertising industry’s best interest and requires equal action from both sides. That means publishers should consistently update their ads.txt files while sellers should audit their sellers.json files, respectively. 

Setupad and all our partners are fully compliant with sellers.json standards. If you have any questions, email us at [email protected] or leave a comment down below. 

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