The ads.txt, sellers.json and SupplyChain object specifications aim to increase transparency at the SSP-level.

They allow the buy-side visibility into the relationships between all transactional players in the programmatic chain. SupplyChain object lets buyers see which sellers and resellers are involved for each bid request.

As an early adopter and strong supporter of the IAB’s efforts to improve quality and transparency, we have posted a sellers.json file that provides the SupplyChain object in the bid requests (except in a server-side bidding context for now).

Five Quality Standards Explained



  • A text file on each publisher domain.
  • Publicly shares the authorized sellers of a web inventory and their directness.



  • A text file on a developer website.
  • Publicly shares the authorized sellers of an app inventory and their directness.


CTV/OTT ads.txt

  • A text file on an inventory partner domain.
  • Publicly shares the authorized sellers of a CTV/OTT channel and their directness.



  • A public .json file on the exchange website.
  • Publicly shares all sellers providing inventory to the exchange and the directness of their business model.


SupplyChain object

  • An object in the bid request.
  • Traces all intermediaries involved in issuing a given bid request.

Smart Works to Increase Transparency

  • We are supporting all market initiatives dedicated to creating an ecosystem that is both transparent and safe.
  • We fully support the IAB in its efforts to improve quality through the sellers.json and OpenRTB SupplyChain object initiatives.
  • You have access to better control and optimized monetization for your inventory.

What Indirect Publishers Need to Do

  1. Host a sellers.json file at the root of your corporate domain that lists all the publishers for whom you are selling your inventory.
  2. Append the SupplyChain object in ad calls or update your prebid.js wrapper, depending on your integration with Smart.
  3. Ensure you are listed in both ads.txt and app-ads.txt files. 

Download our quality standards playbook to learn more about the specifications and what you should do as a publisher.

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Quality Standards Playbook