Next.js 15 + n8n Automated SaaS Starter Kit (Auth, Billing, Email)

Stop wrestling with auth, billing, and emails. Start shipping a production‑ready SaaS in under 60 minutes.

You open your editor to build your SaaS… and immediately lose a week stitching together Next.js auth, Stripe webhooks, email flows, multi‑tenant logic, and security rules you hope are correct. You keep hitting edge cases that no free template covers, and every “quick fix” becomes a late‑night debugging session. You just want a clean, reliable starting point that doesn’t fall apart in production.

This starter kit gives you a fully wired Next.js 15 + n8n SaaS foundation with automated auth, billing, and email. It includes working code, tested workflows, and production‑grade configs — not generic snippets. Drop it in, adjust the env vars, deploy, and you have a functioning multi‑tenant SaaS with secure logins, Stripe subscriptions, and automated emails running end‑to‑end.

What's Included:
• Auth module with JWT + refresh tokens, 8 middleware patterns, and secure session rotation
• Prebuilt Stripe customer, subscription, and billing webhooks with signature validation
• n8n workflows for billing events, dunning, welcome emails, and failed‑payment handling
• Production‑ready RLS rules preventing cross‑tenant access by default
• Multi‑tenant user, org, and role schema with audit logging
• End‑to‑end email templates and triggers for signup, billing, and cancellations
• Vercel + Docker + n8n deployment scripts tested in real production environments
• Token invalidation, webhook retry handling, and safety checks free templates skip

Built from patterns used to ship real subscription SaaS apps with thousands of users, this kit packages the lessons learned from the exact failures indie devs hit: mismatched webhook signatures, insecure auth flows, broken RLS, and deployment configs that only work locally.

Who This Is For:
• Indie devs launching their first SaaS and tired of glue‑coding auth and billing
• Freelancers who need a production‑safe SaaS foundation they can deliver fast
• Technical founders who want reliable multi‑tenant security without learning RLS from scratch

Who This Is NOT For:
• Developers who want to hand‑roll every auth and billing detail
• Teams building a custom backend stack unrelated to Next.js or n8n

Guarantee: If this doesn’t save you at least 10 hours of setup time, reach out for a full refund.

What's Included (12 files)

• lib-n8n-trigger-subscription-renewal.json-—-n8n-workflow-for-Stripe-renewal,-failed-payments,-and-dunning-automation
• scripts-prod-deploy-n8n.sh-—-automated-n8n-env-setup-with-secrets,-SSL,-and-workflow-activation
• db-schema-multi-tenant.sql-—-production‑grade-PostgreSQL-schema-with-enforced-tenant-isolation
• lib-email-templates-welcome-email.html-—-mobile‑responsive-transactional-welcome-email
• app-auth-callback-route.ts-—-secure-OAuth-callback-handler-with-CSRF-+-state-validation
• TROUBLESHOOTING.md-—-fixes-for-common-auth,-webhook,-and-n8n-deployment-issues
• app-api-stripe-webhooks-route.ts-—-fully-validated-Stripe-webhook-processor-with-signature-verification
• db-rls-multi-tenant-policies.sql-—-row‑level‑security-policies-preventing-cross‑tenant-data-leakage
• lib-n8n-trigger-user-signup.json-—-n8n-workflow-that-handles-user-creation,-welcome-email,-and-audit-logging
• scripts-prod-deploy-vercel.sh-—-Vercel‑ready-build-&-environment-bootstrap-script
• lib-auth-tokens.ts-—-secure-signed-JWT-+-refresh-token-rotation-with-invalidation-table
• SETUP-GUIDE.md-—-step‑by‑step-setup-for-Next.js,-n8n,-Stripe,-DB,-and-deployment