title: Nodejs REST API Oauth2 which Grant Type to Use
body: <p>We have a REST API built for our company products listing and user accounts. We want to expose this REST API for external clients so they can use integrate our API into their websites. We have the client domains registered in our database. We will be giving them a API key specific to each client for access to our API. The users from the external sites will be registered via our API using phone number and verification code. Can you please advice me on the Oauth 2 Grant type to be used for authentication in this case?</p>