Supply Chain Transparency (sellers.json & schain)

How Advlume implements sellers.json, ads.txt, and the OpenRTB SupplyChain object (schain) to give DSPs verified transparency over every impression in the chain.

Supply chain transparency is a set of IAB standards that let DSPs and advertisers verify every intermediary in the programmatic chain before placing a bid. Advlume implements two complementary standards: sellers.json (who is selling the inventory) and SupplyChain object / schain (the path the impression took to reach the exchange). Both are active for every impression served through the platform — you do not need to configure anything.

sellers.json

Advlume publishes a sellers.json file at advlume.com/sellers.json. The file lists every entity in the Advlume network that is authorised to sell inventory:

Advlume itself appears as seller_id: "1", seller_type: "INTERMEDIARY" — reflecting that Advlume is the SSP/reseller, not a direct publisher.
Each approved publisher appears as a seller_type: "PUBLISHER" entry with their Advlume internal site ID as seller_id and their domain as domain.

The file is rebuilt automatically whenever a website is approved, rejected, or deleted. DSPs crawl sellers.json periodically (typically every 24–48 hours) to validate that the inventory they are buying is legitimately authorised.

What this means for you

Your domain appears in sellers.json once your site is approved. There is nothing to add or configure — the file is managed entirely by Advlume. If you need to verify your listing, visit advlume.com/sellers.json and search for your domain.

ads.txt

ads.txt is the publisher-side complement to sellers.json. It tells buyers which entities are authorised to sell your inventory. Advlume generates a personalised ads.txt for every publisher, accessible from your site's dashboard under Settings → ads.txt.

Your personalised file includes:

An ownerdomain directive pointing to your domain
A managerdomain=advlume.com directive identifying Advlume as your network manager
A reseller line for Advlume: advlume.com, {your_seller_id}, RESELLER
One line per demand partner (bidder) that Advlume connects to your inventory

The RESELLER entry cross-references your seller_id in sellers.json. DSPs verify that the seller_id in the bid request matches the value in sellers.json and that the domain in sellers.json matches your ads.txt — forming a closed loop of trust.

For setup instructions see ads.txt Setup Guide.

SupplyChain object (schain)

The schain object travels inside every OpenRTB bid request. It declares the ordered list of systems through which the impression passed before reaching the DSP. Prebid constructs the schain from the configuration injected by the Advlume wrapper:

{
  "source": {
    "schain": {
      "ver": "1.0",
      "complete": 0,
      "nodes": [
        { "asi": "advlume.com", "sid": "1", "hp": 1 }
      ]
    }
  }
}

asi — Advlume's domain (advlume.com), matching the domain field in sellers.json
sid — Advlume's own seller ID ("1")
hp: 1 — Advlume is a "hops" participant, meaning it is involved in the payment flow
complete: 0 — The chain may have additional upstream nodes (e.g. the publisher's own SSP if they run a wrapper on top of Advlume); set to 1 only when all hops are declared

Each bidder adapter in Prebid appends its own node before forwarding the request to its exchange, so by the time the bid request reaches a DSP's buy-side platform, it contains the full chain of all involved intermediaries.

How DSPs use these signals

Signal	Where it lives	DSP check
sellers.json	advlume.com/sellers.json	Is the seller_id in the bid request listed? Is seller_type correct?
ads.txt	publisher domain/ads.txt	Is advlume.com authorised to sell this domain's inventory?
schain	OpenRTB bid request (source.schain)	Does the chain match the declared sellers? Are all nodes credible?