Ask HN: Are there any OSS frameworks for site subscriptions?

Since many start-ups need a site with user registration, login, and (optionally) paid subscriptions, you'd think there would be a set of common OSS frameworks for doing that.

For example: a node-based site using Auth0 for identity management, Postgres for user management, Stripe for subscriptions, etc., would seem like a common setup.

Are there just too many variations possible for this to be practical?

Any pointers?