Next.js 15 + Supabase SaaS Starter Kit with Auth & Billing

Stop wasting hours wiring up auth and billing. Start launching your SaaS today.

You open a fresh Next.js app and immediately fall into the same trap: auth that almost works, RLS rules that break under load, subscription logic that fails silently, and webhooks you pray don’t desync. You just want to ship, but instead you're combing through docs, patching permissions, and rewriting boilerplate.

This starter kit gives you a fully working Next.js 15 + Supabase SaaS foundation with 32 production-ready files: hardened auth middleware, multi-tenant RLS policies, complete Stripe and Razorpay billing flows, and a subscription sync function tested against real failure cases. Everything is wired, typed, and ready to run—no guessing, no “why is this 401ing?”, no weekend lost to plumbing.

What’s Included:
- 8 auth middleware patterns with session‑fixation, CSRF, and token‑leakage protection
- Prebuilt email/password signup, login, reset, and magic link flows
- 1 multi‑tenant RLS policy file covering org‑scoped and user‑scoped access
- 6 database schemas with indexes and triggers for SaaS use cases
- Complete Stripe + Razorpay billing flows, including portal and webhook handlers
- 1 production‑tested subscription sync function for reliable state updates
- Admin dashboard with user/org management so you don't build it from scratch
- Starter UI components (navbar, org switcher, profile forms) wired to Supabase
- Docker + env templates for local and production parity

Built from patterns used to ship real SaaS apps serving thousands of users, with security rules reviewed and hardened after handling actual multitenant edge cases. This isn’t theory—these are the configs and flows that prevented support tickets and production outages.

Who This Is For:
- Indie hackers launching a SaaS solo and needing production auth fast
- Developers migrating from Firebase/Auth0 and wanting clean RLS‑based security
- Agencies delivering SaaS prototypes and avoiding fragile custom plumbing

Who This Is NOT For:
- Anyone looking for a no‑code solution
- Teams who already have a fully built auth and billing stack

If this doesn’t save you at least 6 hours of auth setup and 5 hours of billing work, reach out for a full refund.

What's Included (14 files)

• middleware.ts
• app-(auth)-signin-page.tsx
• TROUBLESHOOTING.md
• supabase-functions-handle-subscription-sync-index.ts
• emails-welcome-user.html
• SETUP-GUIDE.md
• components-admin-AdminDashboard.tsx
• emails-invoice-payment-success.html
• lib-razorpay-create-order.ts
• app-(auth)-signup-page.tsx
• supabase-rls-multi-tenant-policies.sql
• app-api-billing-stripe-webhook-route.ts
• app-api-auth-callback-route.ts
• lib-stripe-create-checkout-session.ts