> ## Documentation Index
> Fetch the complete documentation index at: https://developers.criteo.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Managing Sellers

### Overview

In Single-Seller setups, sellers are **not created or managed through MPO**. They exist in your marketplace catalog and are discoverable through the **same MPO Sellers endpoints** used for multi-seller campaigns. This article covers how to find sellers and use their identifiers in Single-Seller workflows.

### The Seller entity

Each seller in your marketplace is represented by a **`sellerId`** — a unique identifier used across MPO endpoints to associate **budgets**, **campaigns**, and **statistics** with a specific seller.

* Sellers are sourced from your **catalog**, not created via MPO.
* The same `sellerId` values used in **multi-seller** campaigns apply in **Single-Seller** setups.

### Discovering sellers

Use the MPO Sellers endpoint to look up `sellerId` values:

```http HTTP theme={null}
GET /marketplace-performance-outcomes/sellers
```

**Example — filter by seller name:**

```http theme={null}
http
GET /marketplace-performance-outcomes/sellers?sellerName=YourSellerName
```

Use the returned `sellerId` values when:

* Creating or updating budgets:
  * `POST /marketplace-performance-outcomes/budgets`
  * `PATCH /marketplace-performance-outcomes/budgets`
* Filtering statistics by seller.
* Configuring `productSet`s on seller-campaigns.

### Syncing your seller list

For automated integrations, fetch and store seller IDs as part of your onboarding flow for each new seller:

1. Call `GET /marketplace-performance-outcomes/sellers` to obtain `sellerId` values.
2. Store them in your system alongside the corresponding `templateCampaignId`.
3. Use the **(`sellerId`, `templateCampaignId`) pair** as the key for all subsequent **budget** and **campaign** operations.