SupaNuxt is a Nuxt3 SaaS boilerplate with key features including user authentication and authorisation, database management with Prisma and Supabase, payment integration with Stripe, state management with Pinia, and server-side rendering. It also includes examples of user profiles, plans and subscriptions, and a notes taking app to demonstrate a sample application. The template aims to provide a solid starting point for developers to build and launch their own SaaS applications.