Vienna, 24.03.2025
A guest commentary by Richard Tuschkany, Founder and CEO of ConnectAd
Admittedly, the headline is provocative and exaggerated – and thanks to a few honorable exceptions in AdTech like Google, Amazon, and AdForm, not entirely accurate. Many advocates of the so-called “Open Internet” present themselves as open-minded, ethical, and diversified – but don’t always live up to those ideals. It’s easy to hide behind one’s own “walled garden,” decorated with a few trendy buzzword graffitis and appealing hedges, making it seem less threatening or restrictive – while still quietly enforcing one’s own rules behind the scenes.
Yet it is precisely the programmatic online advertising world that needs a free, fair, and transparent market – the very definition of the Open Internet. But how open and transparent is it really, when advertisers unknowingly buy inventory through misleading or even falsely labeled paths? Time and again, I find myself questioning whether our industry truly lives up to its promises of transparency. In recent months, we’ve repeatedly discovered that supposedly “direct” supply paths are not always what they claim to be. This issue affects not only advertisers, but also publishers who rely on fair and traceable monetization of their inventory.
Discrepancy Between ads.txt and sellers.json
Two of the most critical transparency tools in the industry are the ads.txt initiative (maintained by publishers) and sellers.json (managed by SSPs or resellers). These are meant to clarify which partners are authorized to sell inventory directly and which are simply resellers. But in practice, it’s not uncommon for reseller relationships to be incorrectly labeled as “DIRECT.”
Things become especially problematic when DSPs (Demand-Side Platforms) fail to rigorously check whether the entries in ads.txt and sellers.json actually match – and end up purchasing falsely declared inventory. The result? Opaque and misrepresented supply chains, leaving advertisers in the dark about where their budgets are actually going.
Why Mislabeling is So Dangerous
Incorrect classifications in the digital advertising market are far from a mere technicality. They can:
- Generate additional hidden costs for advertisers due to middlemen adding margins.
- Increase brand safety risks, as it’s unclear where ads are actually being served.
- Complicate reporting and optimization, as inaccurate delivery paths distort performance measurement.
- Render the oft-used concept of “supply path optimization” completely meaningless – undermining it knowingly or unknowingly.
Anyone who believes they’re buying directly from a publisher might in fact be funding murky reseller chains—at the expense of everyone advocating for a fair and open market.
The Crucial Role of DSPs: Guardians of Transparency?
DSPs bear a unique responsibility here, as they control auction outcomes and a significant part of the value chain. It’s up to them to detect false declarations—or even outright ad fraud—and ensure such inventory is not traded. Yet time and again, we observe gaps in their vetting processes.
When sellers.json files are not properly cross-referenced with ads.txt entries, mislabeling often goes unnoticed – undermining the entire transparency promise of the industry.
What Needs to Change
- Publishers must regularly update their ads.txt files and clearly declare which partners are authorized and under what terms inventory may be sold.
- SSPs must maintain sellers.json files transparently to prevent conflicting or misleading entries.
- DSPs must detect and actively block misdeclared inventory, rather than quietly tolerating or even strategically benefiting from it.
- Advertisers should take a more active interest in how their campaigns are delivered and insist on clear transparency standards.
Conclusion
Our investigations show that while most processes are running correctly and transparently, there are still too many cases where theory and practice diverge. If all market participants truly believe transparency is the cornerstone of the programmatic advertising industry, then we can’t turn a blind eye to mislabeling or disregard for established standards.
The Open Internet is essential for a diverse media landscape and open exchange of ideas – a space that prevents monopolization and ensures powerful platforms don’t dominate the entire digital ecosystem. But for its benefits to be fully realized, advertisers must be protected from inadvertently financing opaque inventory paths. Everyone involved must commit not just to promoting the rules, but to actually following them. Only then can the Open Internet remain a marketplace where advertisers truly get what they pay for – and where transparency is more than just an empty promise.
About the Author
Richard Tuschkany is the Founder and CEO of ConnectAd, an independent, European Supply-Side Platform with a special focus on transparency, quality, and efficiency in the programmatic advertising market.
