Set up the network as a seller

The one-time supply-chain setup of the network — the seller domain, Publish sellers.json and its contact address, the network-wide ads.txt / app-ads.txt lines with OWNERDOMAIN and MANAGERDOMAIN, and listing the sites you sell — step by step.

How-to network manager admin publisher Admin → White Label → Supply chain

What it is and why

Before any site or partner can be set up, the network itself is named as a seller: the domain buyers know you by, the sellers.json published at that domain, and the ads.txt lines every site you sell must carry. You do this once, in Admin → White Label → Supply chain, then opt in the sites you sell. The scenarios on Supply chain, sellers.json and ads.txt: setup by scenario add what each site or partner needs on top of it.

Example. The network Northwind Ads sells Sports Daily to DSPs. The bid request says asi: northwind-ads.example, sid: 4831207; https://northwind-ads.example/sellers.json lists seller 4831207 as Sports Daily Media Ltd, sportsdaily.example; and https://sportsdaily.example/ads.txt contains northwind-ads.example, 4831207, DIRECT. The seller domain and the published sellers.json are the network setup; the listed site is step 4.

Typical scenarios

You want	Set	Where
Buyers to verify your seller IDs at `https://northwind-ads.example/sellers.json`	Seller domain `northwind-ads.example`, Publish sellers.json on, the contact address	Admin → White Label → Supply chain
An SSP that sells every site (`meridian-ssp.example, MRD-5512, RESELLER, 7c1e2a90b3d54f6a`) in every publisher’s block	Its line in ads.txt / app-ads.txt lines	Admin → White Label → Supply chain
Your manager line in every site’s file, with a US-specific one	`MANAGERDOMAIN=northwind-ads.example` and `MANAGERDOMAIN=northwind-ads.example, US`	Admin → White Label → Supply chain
The sites you sell listed in sellers.json, staging sites kept out	List in sellers.json on those sites only	The site, or the sites grid

Step by step

The one-time network setup comes first; each scenario then adds what it needs.

Name the network as a seller. In Admin → White Label → Supply chain, set Seller domain to the domain buyers know you by, for example northwind-ads.example. Point that domain at the platform so https://northwind-ads.example/sellers.json reaches it.
Switch on Publish sellers.json and fill sellers.json contact address. The contact e-mail is the Email in Company info.
Add network-wide ads.txt lines, if a partner sells every site you have: paste its block into ads.txt / app-ads.txt lines on the same page. Invalid lines are refused on save, with their line numbers. OWNERDOMAIN= and MANAGERDOMAIN= are set here and nowhere else: one OWNERDOMAIN, and one MANAGERDOMAIN per country (MANAGERDOMAIN=northwind-ads.example, US; the one without a country is the global one). A second one is refused on save. MANAGERDOMAIN opens every site’s file. OWNERDOMAIN names the site’s owner, so it opens only the files of the sites you own yourself — those nobody owns or your admin user owns, which sellers.json lists under your own name; a publisher adds its own. CONTACT= and SUBDOMAIN= belong to the publisher’s own file and are refused here as well; lines saved before that are left out of every block.
Opt sites in. Turn on List in sellers.json on each site you sell, or select sites in the sites grid and press List in sellers.json.

Then pick the scenario that matches each site or partner — the overview is on Supply chain, sellers.json and ads.txt: setup by scenario.

Caveats and exceptions

The supply chain in DSP bid requests does not depend on List in sellers.json. List every site you sell to DSPs with the chain switched on, or buyers will not find its seller ID.

The caveats that apply to every supply-chain setting — who can do this, what a seller ID change touches, which line the network’s own entry is — are on Supply chain, sellers.json and ads.txt: setup by scenario.

Not working?

A pasted line is refused on save. Where: the message names the line number. OWNERDOMAIN and MANAGERDOMAIN take one entry each (one MANAGERDOMAIN per country); CONTACT= and SUBDOMAIN= belong to the publisher’s own file. Delete the line and save again.
A site is not in sellers.json. Where: the site’s List in sellers.json switch, or the sellers.json column of the sites grid — sites start unlisted.
sellers.json does not open at your seller domain. Where: the domain’s DNS — it has to point at the platform for https://<seller domain>/sellers.json to reach it.

The causes of Missing lines: N, File not found and Could not check on a site are on Supply chain, sellers.json and ads.txt: setup by scenario.

Reference

Every setting and where it lives, and the terms: Where things live and Glossary on the hub. The sellers.json fields and the file’s shape: Supply chain and sellers.json.