An external token provider is a type of entity in the payment industry with its own flow that typically collects the customer payment method and transaction details. In some cases, it performs 3D Secure (3DS) authentication and provides the 3DS authentication values. The first time a customer uses a card with the external token provider, the external token provider performs 3DS authentication and stores the 3DS values from the successful authentication in a token.
Nuvei REST API 2.0 supports non-3DS payments with these external token providers: