The following will describe how the Login API can be integrated with Auth0 to achieve a better flow for user registration and payment. The login and payment flow can be implemented both separately and together. Implementing the flows together allow users to be registered during payment and later log in as a registered user.
Auth0 is a customer identity management solution. Learn more about it on the Auth0 pages.
These guides describe how to use the Login APIs with Auth0. The login guide will help you to configure Vipps as an identity provider in Auth0 and retrieve contact info from the user that logs in.