Create or Update a Customer

Creates a new customer record in the merchant account. In cases when the customer was not created at the time an Authorization was established, use this endpoint to register customer details, such as name, email, and optional metadata, to support your integration.

If an existing customerId or externalId is provided, the specified customer will be updated with any new or updated properties. To remove properties of an existing customer, set the property to null. Before using this endpoint, it may be helpful to call Get Customer by ID to obtain the relevant customer object.