---
title: "Set up the network as a seller"
description: "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."
type: "howto"
audience: [network-manager, admin, publisher]
keywords: [seller domain, sellers.json, Publish sellers.json, sellers.json contact address, network-wide ads.txt lines, app-ads.txt lines, OWNERDOMAIN, MANAGERDOMAIN, CONTACT, SUBDOMAIN, List in sellers.json, sites grid, White Label supply chain, invalid lines refused]
ui_path: "Admin → White Label → Supply chain"
---

Fetch the complete documentation index at: https://epom.com/ad-server/docs/llms.txt. Use this file to discover all available pages before exploring further. Append .md to any documentation page URL to get its markdown version.

# Set up the network as a seller

## 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](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md) 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.

1. **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.

2. **Switch on Publish sellers.json** and fill **sellers.json contact address**. The contact e-mail
   is the **Email** in Company info.

3. **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.

   ![White Label Supply chain section](https://epom.com/docs-images/ad-server/supply-chain-ads-txt-setup/white-label-supply-chain.webp)

4. **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**.

   ![Sites grid with sellers.json and ads.txt columns](https://epom.com/docs-images/ad-server/supply-chain-ads-txt-setup/sites-grid-supply-chain.webp)

Then pick the scenario that matches each site or partner — the overview is on
[Supply chain, sellers.json and ads.txt: setup by scenario](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md#step-by-step).

## 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](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md#caveats-and-exceptions).

## Not working?

1. **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.
2. **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.
3. **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](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md#not-working).

## Reference

Every setting and where it lives, and the terms:
[Where things live](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md#where-things-live) and
[Glossary](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md#glossary) on the hub. The sellers.json fields and the
file's shape: [Supply chain and sellers.json](https://epom.com/ad-server/docs/guides/inventory/supply-chain-and-sellers-json.md).

## Related

- [Supply chain, sellers.json and ads.txt: setup by scenario](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup.md)
- [Supply chain for DSPs and header bidding](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup-dsp-and-header-bidding.md)
- [Demand partners' ads.txt lines](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup-demand-partners.md)
- [Intermediary sites and CTV channels](https://epom.com/ad-server/docs/guides/inventory/supply-chain-ads-txt-setup-intermediary-and-ctv.md)
- [Supply chain and sellers.json](https://epom.com/ad-server/docs/guides/inventory/supply-chain-and-sellers-json.md)
- [White label](https://epom.com/ad-server/docs/guides/admin/white-label.md)