I'm a recent and big fan of Hydra. One of my biggest issues with OAuth provider libraries is how tied you usually are to specific authentication implementation

I'm a recent and big fan of Hydra. One of my biggest issues with OAuth provider libraries is how tied you usually are to specific authentication implementations and if you want to go outside that, things get complex, fast. They've concentrated just on the backend parts of being a provider, passing responsibility for authentication, signup, password resets, etc to a challenge app you write yourself.