Next.js 15 SaaS Starter Kit

Developers building SaaS products waste 35-50 hours on repetitive boilerplate — wiring up authentication, payments, CMS integration, and AI features before writing a single line of business logic.

I designed and built a complete, production-grade SaaS starter kit from scratch — a $99 digital product that saves developers 40+ hours of setup time.

Authentication System — Login, signup, and forgot-password flows powered by Payload CMS built-in auth. Route protection via Next.js middleware with server-side session management.

Stripe Payments — Complete subscription billing with Checkout sessions, a webhook handler for 4 event types (checkout completed, subscription updated/deleted, payment failed), Customer Portal integration, and a Subscriptions collection for tracking.

Dashboard UI — A premium dark-mode dashboard with a collapsible sidebar, posts CRUD, user settings, and an AI playground. Built with 5 reusable UI components (Button, Input, Card, Badge, Toast) using Tailwind CSS and Framer Motion.

Gemini AI Integration — Structured JSON generation with retry logic and exponential backoff, plus streaming chat via Server-Sent Events. Includes a built-in AI playground page for testing prompts.

Email System — Resend integration with React Email templates for welcome and password-reset flows. Graceful console fallback when no API key is configured.

Full Test Suite — 21 unit tests across 5 Jest test suites covering the Gemini helper, auth sessions, Stripe webhooks, AI routes, and UI components. Plus 2 Playwright E2E specs.

DevOps — Multi-stage Dockerfile, docker-compose.yml, health check endpoint, and AGENTS.md for AI coding assistant integration.

60+ hand-crafted files — zero auto-generated boilerplate filler

Clean production build — compiles with zero TypeScript errors and zero ESLint warnings

21/21 tests passing — verified before every release

Zero proprietary references — fully generic, white-label boilerplate

Modern stack — Next.js 15 App Router, React 19, Payload CMS 3 with SQLite, Zod 4, Tailwind CSS

Next.js 15 · React 19 · TypeScript · Payload CMS 3 · Google Gemini AI · Stripe · Resend · Tailwind CSS · Framer Motion · Jest · Playwright · Docker