What is supply path optimization?
Supply path optimization, or SPO, is the practice of buying through the fewest and most direct routes to a publisher, so more of each dollar reaches the publisher and you can see where the rest went.
Why does the path matter?
Between an advertiser and a publisher sit agencies, trading desks, buying platforms, selling platforms, exchanges, data providers, verification vendors and resellers. Each layer does something, and each layer takes a cut. The same publisher inventory can also reach you through several routes, at different fees. Choosing the route is a buying decision, not a technical detail.
How does SPO work in practice?
- Map the paths. List every route your spend takes to each publisher or app.
- Compare the routes. For the same inventory, compare fees, quality and outcomes.
- Shift spend. Move budget to the direct or best-performing route.
- Keep checking. Paths change, so the map needs a regular refresh.
Which standards make a path visible?
- ads.txt. A file on a publisher’s domain that lists who is authorized to sell its inventory.
- sellers.json. A file a selling platform or exchange publishes, listing the sellers it represents and whether each is a publisher or an intermediary.
- The supply chain object. Information carried in the bid request that lists each company that handled it.
ViSTARS, Inc. publishes its own sellers.json at vistars.ai/sellers.json.
What does SPO not solve?
A short path is not automatically a good path. You still need to check where your ads ran, including made-for-advertising sites and spoofed CTV, and how conversions are counted. A cheaper route that delivers poor inventory can cost more than it saves.
How can I check my own paths?
Ask your agency or platform these questions, and ask for the answers in writing.
- Which suppliers sit between my budget and the publisher?
- What does each one take, in fees, margins and rebates?
- Do you buy direct, or through resellers?
- Can I audit the logs and the invoices?
- Who owns the data from my campaigns?
How is this related to a Supply Path Review?
A Supply Path Review applies this to your own spend. We follow it from budget to impression, then write down who took what and what to change. You keep the report either way.