You can create and manage customers with the BillPro API.

BillPro identifies customers with the unique system identifier, which is the id attribute.
In the API, BillPro also assigns a 10-digit alphanumeric customer_id, which you cannot modify using the API.
- In the UI, when you create a customer you can create a customer_id and you can also modify it.
- This is also referred to as the merchant customer ID
When you list customers, you can filter by the customer_id.

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Customer ID when creating an order
When you create an order for a customer, you must specify the customer using the system customer id. In an order body object, this attribute is called the customer_id!