The 60 Second Supply Path Check Every Marketer Should Run

By Maaz A. Khan, Regional Client Partner (APAC), WPP Media

Programmatic advertising makes it easy to launch campaigns. It is harder to answer a basic question: where did my budget go on its way to the publisher?

Marketers see performance numbers, reach, and CPMs. What we do not always see is the route our spend took, how many intermediaries touched it, and whether selling relationships were clearly stated. When that route gets messy, confidence drops. You can still get impressions, but it becomes harder to know if you are buying the cleanest path, paying unnecessary fees, or taking avoidable supply risk.

This matters for three practical reasons. First, complexity often means cost. Each additional hop can introduce fees and reduce control. Second, ambiguity makes it harder to validate quality. If you cannot explain who is authorized to sell inventory and how you are accessing it, it becomes tough to defend decisions internally, especially when procurement and finance ask reasonable questions. Third, the supply chain changes. Relationships can shift between quarters, and what was true last month may not be true today.

A simple starting point is a file called ads.txt. Think of ads.txt as a public list a publisher uses to declare who is authorized to sell their inventory. It is not the whole story, but it is one of the easiest transparency signals available. If this layer is unclear, everything above it becomes harder to validate.

Getting ads.txt is straightforward. In a browser, type the website domain followed by /ads.txt (for example, example.com/ads.txt). It opens as plain text. You can copy the contents into a text file named ads.txt, or paste it directly into a checker.

What should marketers look for?

Start with relationship clarity. In ads.txt, sellers are typically labeled as DIRECT or RESELLER. If the same seller appears as both for the same account, it can create ambiguity. In plain terms, it becomes less clear who is actually selling what and through which role. That is a prompt to ask your agency or publisher to confirm the intended relationship and the preferred route.

Next, watch for suspicious or non standard entries. Sometimes ads.txt includes lines that do not look like standard domains or include unusual account patterns. This is not automatically fraud, but it is worth checking because configuration mistakes can create confusion for buyers and platforms, and can lead to supply being accessed in ways that were not intended.

Finally, note transparency gaps. Some entries include optional identifiers that support verification in parts of the ecosystem. Missing identifiers are common and not always wrong, but they can reduce traceability depending on partners. For a marketer, this is mainly a signal to lean into higher quality paths and ask for a clear explanation of the route being used, rather than a verdict on a publisher.

How does this translate into action? Pick the sites you spend meaningfully on. Run a quick check. Bring a small number of findings into your next optimization discussion. The goal is not to police every line. The goal is to reduce uncertainty, shorten paths where possible, and align buying with transparency. Even one or two better questions can improve how your agency prioritizes supply.

If something looks off, ask: Which path are we prioritizing for this publisher? Can we limit to preferred sellers or direct routes where available? What changes if we choose the cleanest route, even if CPM is slightly higher? Can we document the rationale so stakeholders understand the trade off?

This is why I built AdChainAudit, a small open source tool designed for marketers and media teams. It takes an ads.txt file, highlights buyer relevant red flags with line level evidence, and generates a shareable report you can use with agencies, publishers, and procurement. The idea is not to turn marketers into ad tech engineers. The idea is to make it easier to ask better questions and build healthier buying habits over time.

Try it: https://adchainaudit.streamlit.app/

Project page for technical users: https://github.com/maazkhan86/AdChainAudit