# Merchant-hosted API

> Direction: Recustomer → Merchant

The API Recustomer calls when it needs to retrieve or update data in the merchant's system. Implement the endpoints in the merchant's system.

Recustomer calls only the APIs configured as integration targets in the admin screen. See "APIs used by each feature" in the Introduction for which feature uses which API.

## Authentication
You need to implement <b>token authentication</b> in the merchant's environment.
Recustomer sends API requests to the merchant's environment with the token in the "api_token" header.
Provide the access token to Recustomer on the external service integration screen.