Our API supports 3 of the standard OAuth Authorization protocols, all of which require manual action in the authentication flow.
If you are a partner, you are able to request access to Certificate Based Authentication (CBA), which enables fully automated login process without manual, human input. This authentication method is available for server-to-server integrations, and requires no manual input to authenticate users.
Due to regulatory requirements, CBA unfortunately cannot be made available to retail clients. The best and closest login behavior a retail client can achieve is to extend the session by continuously requesting refresh tokens, after manually logging in once.
More Resources
GitHub - Examples on retrieving and refreshing the authentication token
