Next.js SaaS Starter is an MIT-licensed template for launching a SaaS on Next.js 15 (App Router). It wires together authentication, Stripe subscriptions, team management and a polished dark-first dashboard, so developers can skip weeks of boilerplate and start on the actual product. Auth runs entirely inside your own app, no Clerk, Auth0 or Supabase account to sign up for. Also included: Stripe Checkout, customer portal, webhooks and the full subscription lifecycle, team invites and permissions, PostgreSQL with Drizzle ORM, Tailwind CSS v4. One-click deploy to Vercel, or host it anywhere. Source: https://github.com/mailkite/saas-startup
I run MailKite, and every time I started a new project I rebuilt the same three things: auth, billing and teams. So I built the version I actually wanted, self-contained, MIT licensed, with the auth code sitting in my own repo. It was going to sit in a private folder either way, so I open-sourced it.