SellersjsonEdit
Sellersjson, commonly written as Sellers.json, is a data standard used in the digital advertising ecosystem to publish structured information about the entities that sell a publisher’s inventory. It is hosted on the publisher’s domain as a machine-readable JSON document and is designed to be read by buyers, exchanges, and intermediaries across the programmatic supply chain. By making who is selling what inventory more transparent, the standard aims to reduce confusion, cut down on fraud, and improve the efficiency of market transactions.
The standard sits alongside other transparency initiatives in the ad-tech space, notably ads.txt, and is maintained by the industry body responsible for setting and updating technical specifications in this space, the IAB Tech Lab. Unlike regulatory mandates, Sellers.json is voluntary and market-driven, reflecting a pragmatic approach to improving trust in a high-volume, fast-moving marketplace. Supporters argue that it aligns with the broader preference in free markets for clear property rights and verifiable information, enabling buyers to make better decisions and publishers to preserve direct relationships with advertisers.
From a design perspective, Sellers.json is part of a broader push to illuminate the actual sources of inventory in the programmatic chain. By listing the sellers and the nature of their relationship to the publisher (for example, direct sellers versus resellers), it helps advertisers and their partners verify who is responsible for a given impression. This, in turn, tends to reduce revenue leakage and misattribution, supporting healthier competition and more accurate pricing signals in the marketplace. Practices and data formats are intended to be interoperable with other standards in the ad-tech stack, including the commonly used OpenRTB protocol and other industry tools that manage bids, targeting, and attribution. Related concepts include the broader world of digital advertising and the ongoing effort to bring greater supply chain transparency to online media.
Overview
What it is: a machine-readable JSON file hosted on a publisher’s site that lists the entities allowed to sell that publisher’s inventory and describes their selling relationship. The document helps buyers verify the provenance of each impression.
Core idea: provide a clear, auditable map of who is selling inventory, reducing misrepresentation and fraud without requiring heavy-handed regulation.
Relationship to other standards: complements the earlier ads.txt file by focusing on the sellers themselves and the nature of their authority, rather than solely on which domains are authorized to sell. See also IAB Tech Lab and OpenRTB for the broader technical ecosystem.
Scope and use: used by advertisers, ad exchanges, and DSPs to verify supply chain integrity during the bidding and delivery process. It is a market, not a government, solution to a shared problem in the ad marketplace.
Core elements
seller_id: a stable identifier for the selling entity as recognized across the ecosystem.
domain: the publisher’s domain or another domain associated with the seller’s identity.
seller_name: public name of the selling entity.
relationship_type: categorizes the seller as DIRECT or RESELLER, clarifying how the inventory is being sold.
optional fields: additional metadata that can help buyers understand the context and governance around the seller, without compromising proprietary information.
Technical framework
Sellers.json is designed to be simple to publish and straightforward to consume. A publisher can host a Sellers.json file at a predictable location on their site, and buyers can fetch and parse the data as part of their standard operating procedure for purchases. The JSON structure is designed to be machine-readable, enabling automated checks for consistency between what a publisher claims in their ads.txt and what they disclose in Sellers.json. This alignment supports efficient auditing and helps maintain the integrity of the ad-buying process.
Industry participants—including major publishers, ad exchanges, and demand-side platforms—benefit from a common, transparent reference point about who is selling inventory and under what authority. The standard’s compatibility with the broader ad-tech ecosystem means it can be used in conjunction with other tools and workflows without imposing heavy administrative burdens. This fits a market-oriented view that values voluntary, interoperable standards over top-down regulation.
Adoption and impact
Adoption of Sellers.json has grown as publishers and buyers recognize the benefits of supply-chain transparency. For publishers, the standard helps safeguard brand safety by making direct relationships explicit and reducing the risk of misattribution in auctions. For advertisers and agencies, it provides a clearer picture of where their dollars are going, enabling them to route spend toward inventory with verifiable provenance. Industry observers often contend that improved transparency leads to more accurate pricing, better performance measurement, and healthier competition among sellers and intermediaries.
As with any industry standard, there are costs and caveats. Smaller publishers may face technical or resource constraints in implementing Sellers.json, though many content management systems and ad-tech providers offer support or turnkey integrations. Regulators have not mandated the standard, and the market’s voluntary adoption means that widespread benefits depend on continued buy-in from publishers and the buyers who rely on the data. The net effect, when broadly adopted, is typically framed as a straightforward improvement in information quality that supports efficient, outcome-oriented marketplaces.
Controversies and debates
Privacy and data exposure: some critics worry that publishing seller relationships could reveal business arrangements that publishers would prefer to keep confidential. Proponents counter that the information disclosed is business-facing, not customer-level data, and that the transparency benefits for the market as a whole outweigh concerns about competitors learning every nitty-gritty detail.
Regulatory vs market-driven approach: opponents of voluntary standards may advocate for formal government mandates or heavier regulation to enforce transparency. Proponents of a market-based approach argue that voluntary standards can move faster, adapt to technology, and avoid the distortions that come with heavy-handed regulation. The discussion often centers on which path yields the best balance between consumer protection, innovation, and market efficiency.
Burden on small publishers: critics warn that compliance costs could be prohibitive for smaller sites or independent publishers. Supporters reply that the economics of transparency pay off through improved monetization, reduced fraud, and clearer direct relationships; they also note that tooling and services are increasingly available to lower the barrier to entry.
Widespread skepticism about woke critiques: some critics in this space contend that broader cultural or political critiques about data practices miss the practical, market-based logic of transparency standards. They argue that the core aim—reducing fraud and clarifying supply chains—serves legitimate business interests and consumer expectations without becoming a vehicle for unrelated agendas.
See also