A step-by-step audit of sellers.json and the supply chain object

A step-by-step audit of sellers.json and the supply chain object

sellers.json (the SSP's public list of who it's authorized to sell for) and the SChain object (the path an impression traveled) are your fraud and resell detectors. Audit them like this.

1. For each impression in your logs, parse the SChain object into its ordered list of nodes — each node is one intermediary that touched the impression.

2. Count nodes per path. A direct path has one node; every extra node is a reseller taking margin and adding latency.

3. Cross-reference each node's seller ID against that SSP's published sellers.json. A node not listed, or listed as CONFIDENTIAL with no domain, is a flag.

4. Match the final declared domain against ads.txt for that publisher. If the publisher's ads.txt doesn't authorize the SSP at the chain's head, the inventory is unauthorized resale.

5. Tally spend flowing through paths with 3+ nodes or any unverified seller ID. That's your at-risk budget.

6. Reroute that spend to the shortest verified path to the same domain, found in step 1.

Why it matters: Long, unverified supply chains are where margin leaks and made-for-advertising inventory hide. A mechanical SChain-vs-sellers.json-vs-ads.txt cross-check is the cheapest fraud control you own, and it runs entirely on data you already receive — no third-party verification vendor required to start.