Cobbler

Cobbler is deliberately small. It adds to a fresh Rails 8 app: the built-in authentication with email confirmation, a user settings page, Stripe Checkout and the customer portal through a single webhook controller, Tailwind styles, a mailer layout and a Kamal config for SQLite on one server. There are tests for each flow and a short setup guide.

The maintainer is opinionated that a starter should be something you could have written yourself in a weekend, just already written. Nothing is abstracted into gems or concerns you need to learn. The limitation: it stops early. There are no teams, no admin, no i18n, and the Stripe integration does not handle plan changes inside the app.