The Paper Trail Problem: Do ads.txt and sellers.json still protect Indian buyers?

A programmatic campaign can deliver millions of impressions, meet its cost-per-thousand-impressions target and generate a reassuring performance report, yet leave an uncomfortable question unanswered: how much does the advertiser really know about the inventory it has purchased?

The question becomes more complicated when an impression passes through several advertising platforms before reaching the buyer. A publisher may rely on multiple supply-side platforms, an exchange may work with resellers, and a demand-side platform may receive inventory through several routes. By the time the transaction reaches the advertiser, the original source can be difficult to assess without examining the underlying supply-chain data.

This is the problem that ads.txt and sellers.json were designed to address. They give buyers a way to investigate authorised selling relationships and identify the businesses participating in digital advertising transactions. Yet, years after their introduction, the existence of these standards has not eliminated concerns about opaque inventory, unnecessary intermediaries or questionable advertising environments.

For India’s programmatic advertising market, where brands are distributing budgets across websites, mobile applications, video platforms and connected television, the distinction between having transparency tools and using them effectively is becoming increasingly important.

The gap between a successful campaign and a transparent one

Programmatic buying has made it easier to purchase advertising at scale. It has also made the mechanics of that purchase less visible to many marketing teams. Campaign dashboards typically foreground reach, impressions, clicks, conversions and cost efficiency. The route through which those impressions entered the auction can receive considerably less attention.

That imbalance matters because a campaign’s reported performance does not necessarily establish the quality or legitimacy of its supply. An inexpensive impression may be commercially useful, but it may also come from an environment that offers little value to the brand. A high volume of impressions may indicate strong reach, or it may reflect placements that warrant closer scrutiny.

Advertisers need to distinguish between three questions. Is the seller authorised to sell the inventory? Is the inventory being represented accurately? And is the inventory worth buying? These questions are connected, but they are not interchangeable.

Ads.txt and sellers.json primarily help address the first question and provide information relevant to the second. They do not independently settle the third. That distinction is essential to understanding both the value and the limitations of the standards.

What the files reveal — and what they leave out

Ads.txt, developed through the IAB Tech Lab’s advertising technology standards programme, allows a publisher to declare the advertising systems and seller accounts authorised to sell its inventory. The file is hosted on the publisher’s domain, giving buyers a public record against which seller information can be checked.

Its principal purpose is to make it harder for unauthorised parties to misrepresent inventory. If a bid request claims to represent a publisher, the buyer can compare the declared seller account with the publisher’s authorised list rather than relying entirely on the information accompanying the bid.

Sellers.json provides a complementary record. Advertising systems publish information about the sellers represented by their accounts, helping buyers connect account identifiers with business entities and understand the role those entities play in the transaction.

The OpenRTB SupplyChain object adds another layer by describing the declared sequence of sellers and intermediaries involved in an individual advertising opportunity. Together, these mechanisms help buyers examine the relationship between the inventory, the seller and the route through which it reaches the auction.

The limitation is that these mechanisms depend on declarations and the systems that interpret them. A file can exist without being accurate. An authorised seller can offer inventory that is unsuitable for a particular advertiser. A buying platform can receive useful transparency data without necessarily applying rigorous checks to every transaction.

In other words, the standards provide evidence to examine, not an automatic guarantee of trustworthiness.

When authorised supply still raises questions

Consider a hypothetical campaign for a financial services brand seeking to reach readers of established news publications. The publisher lists its authorised advertising partners in ads.txt. One of those partners supplies the inventory through a network of additional intermediaries, each participating in the transaction for a commercial or technical reason.

The initial seller may be authorised, but that fact alone does not explain the entire route. Buyers still need to establish which entities participated, whether the declared relationships are consistent, and whether each additional layer serves a meaningful purpose.

Some intermediaries bring genuine value. They may aggregate fragmented inventory, provide access to specialist audiences or support transactions that would otherwise be difficult to execute. Their presence should not automatically be interpreted as a warning sign.

The problem arises when buyers cannot distinguish useful intermediation from unnecessary complexity. Multiple routes to the same publisher can make costs harder to compare, while inconsistent identifiers or incomplete supply-chain information can weaken the buyer’s ability to determine where an impression originated.

This is why supply-path optimisation has become relevant to the transparency debate. The objective is to evaluate the routes through which inventory is purchased and identify those that offer the best combination of quality, cost, reach and accountability.

A shorter route may reduce complexity, but it is not inherently superior. A more direct transaction could deliver less reach or weaker performance than an alternative route. The commercial decision should be based on evidence rather than a blanket preference for fewer intermediaries.

For agencies, this means moving beyond a list of approved exchanges. They need to understand the actual supply paths used by campaigns and be able to explain why those paths have been selected.

India’s market makes the question harder to ignore

India’s digital advertising ecosystem is not a single, uniform marketplace. It includes established publishers, regional-language websites, mobile-first platforms, gaming applications, streaming services and smaller digital businesses serving specific audiences.

This diversity is commercially valuable. A regional publisher may offer access to consumers whose interests and language preferences are poorly represented elsewhere. A specialist application may provide a relevant environment for a particular campaign. A smaller property should not be judged negatively simply because it lacks the scale of a national media brand.

At the same time, the variety of inventory sources increases the need for consistent standards of verification. An advertiser running campaigns across several languages, platforms and formats cannot assume that every seller relationship will be equally easy to assess.

For agencies managing multiple clients, the challenge is particularly practical. Supply-chain checks must be repeatable across campaigns, supported by clear documentation and adapted to the environments being purchased. Waiting until a client questions a placement or a campaign produces an unexpected result is a weak substitute for ongoing oversight.

Marketing teams should also understand that transparency is not solely the responsibility of their buying platform. Publishers must maintain accurate authorised-seller declarations, supply-side platforms must provide reliable seller information, and demand-side platforms must interpret the available records correctly. Agencies must ensure that these controls translate into purchasing decisions.

Advertisers, meanwhile, should ask their partners to explain the process in concrete terms. Which checks are performed? How are discrepancies handled? What proportion of supply cannot be adequately verified? Can the agency explain why a particular source was included or excluded?

These questions turn a broad promise of transparency into something that can be evaluated.

CTV and mobile apps expose the limits of a website-first approach

As Indian advertisers expand their investments in connected TV and app-based environments, supply-chain scrutiny must account for inventory that does not behave like conventional web advertising.

In connected TV, a campaign may run across streaming applications, smart-TV environments and advertising-supported video services. The company selling the impression, the application hosting the content and the platform delivering the bid request may be different entities.

App-ads.txt extends the authorised-seller approach to mobile applications and connected TV applications. It gives developers a mechanism to declare authorised advertising sellers, helping buyers establish whether a platform has permission to represent an application’s inventory.

However, verifying an authorised seller does not establish that every other aspect of the impression is accurate. It does not independently confirm that the advertised application was the one claimed, that the traffic was legitimate or that the audience and placement met the advertiser’s expectations.

These questions require additional verification and measurement. Buyers need appropriate checks for application identity, invalid traffic, placement quality and campaign delivery. They should also examine whether reporting provides enough detail to distinguish between individual applications and inventory sources.

The same principle applies to mobile advertising. An authorised relationship is a useful starting point, but it should not replace scrutiny of the environment in which an advertisement appears or the quality of the traffic it generates.

For advertisers, the implication is that transparency standards must be part of a broader quality framework. They establish important facts about the supply chain, but they cannot independently certify the complete advertising experience.

The MFA problem: legitimate transactions, questionable value

Made-for-advertising websites present a particularly useful example of why authorisation and quality must be assessed separately. These properties are generally designed to generate advertising revenue, often through high volumes of content and advertising placements, rather than prioritising a substantial audience experience.

A website of this kind may have declared its advertising partners correctly. Its inventory may be sold through authorised accounts, and its supply-chain records may appear consistent. Yet an advertiser may still question whether the environment contributes meaningful attention, audience value or brand suitability.

This is not necessarily a question of fraud. It is a question of commercial judgement. An inventory source can be technically transparent and still be a poor fit for a campaign.

Advertisers should therefore avoid treating ads.txt compliance as a substitute for publisher evaluation. Domain-level performance, content quality, engagement patterns, placement characteristics and traffic-quality signals can all help determine whether a source deserves investment.

Agencies also need to look beyond low CPMs. Cheap impressions can make a campaign appear efficient, but cost efficiency has limited meaning when the inventory does not reach the intended audience or contribute to the campaign’s objective.

The response should be evidence-led rather than indiscriminate. Smaller or unfamiliar publishers should not be excluded simply because they are less well known. Instead, brands should establish clear criteria for acceptable inventory and investigate sources that fail to meet them.

What a serious transparency process looks like

The practical test for ads.txt and sellers.json is whether they change the way media is bought. If the files are checked only during onboarding and never revisited, their usefulness diminishes as seller relationships and supply arrangements evolve.

A more effective process begins with regular validation. Buying systems should check relevant seller declarations, compare account identifiers and flag discrepancies. When supply-chain information is incomplete or inconsistent, the next step should be investigation, not an automatic assumption that the inventory is acceptable.

Buyers should also review the declared SupplyChain object wherever it is available and relevant. Comparing its participants with ads.txt and sellers.json records can help identify unexplained intermediaries, missing information or relationships that require further examination.

Reporting should then translate those findings into commercial terms. Advertisers need to understand where their budgets are going, which sources meet their standards and which routes introduce avoidable complexity. Technical compliance rates alone will not tell a marketing director whether a campaign is delivering the right audience at an appropriate cost.

Contracts and partner agreements should clarify responsibilities for maintaining seller records, transmitting supply-chain information, responding to discrepancies and supporting audits. These expectations are especially important when several technology partners are involved in the same campaign.

Finally, transparency controls should be evaluated against outcomes. If changing a supply path reduces cost without damaging reach or performance, the change may create value. If a supposedly cleaner route produces weaker results, the buying decision needs to be reconsidered. The purpose is not to optimise for compliance in isolation, but to improve the quality and accountability of media investment.

Why technology alone cannot close the gap

The programmatic industry continues to develop standards and tools that address different aspects of transaction integrity. Ads.txt, sellers.json and the SupplyChain object help buyers understand authorised selling relationships and declared intermediaries. Other approaches, including transaction-security measures such as ads.cert, address separate risks and can complement the broader framework.

None should be mistaken for a universal guarantee. A technically valid transaction may still deliver unsuitable content, weak attention or limited business value. Equally, a discrepancy in a record may require investigation rather than an immediate conclusion that fraud has occurred.

This is where human oversight remains essential. Agencies need specialists who can interpret supply-chain data, distinguish technical errors from material risks and explain the commercial consequences to clients. Advertisers need procurement and marketing teams that understand the questions to ask, even if they do not inspect every technical record themselves.

The industry also needs to resist the temptation to reduce transparency to a checkbox in a media plan. A platform’s ability to support a standard is only the beginning. What matters is whether the platform validates the relevant data, makes the results accessible and allows buyers to act on the findings.

The real test is what buyers do with the information

Ads.txt and sellers.json have not become irrelevant. If anything, the growing complexity of digital media makes the ability to identify authorised sellers and examine supply paths more important.

But their role needs to be understood correctly. They cannot tell an advertiser everything about the quality of an impression, and they cannot independently eliminate every form of fraud, waste or poor-value inventory. They make certain aspects of the transaction more visible, giving buyers a stronger basis for scrutiny.

For Indian advertisers, the next step is to make that scrutiny routine. Agencies should verify rather than assume, examine supply paths rather than rely on aggregate reports, and connect technical checks with campaign objectives. Publishers and technology platforms should maintain accurate records and make accountability part of their commercial relationships.

The measure of progress will not be how many partners claim to be compliant. It will be whether advertisers can explain where their money went, why a particular inventory source was selected and what evidence supports the decision.

In programmatic advertising, trust cannot rest on declarations alone. It has to be built through verification, transparent reporting and the willingness to question a transaction even when its performance dashboard looks convincing.