Next.js SaaS boilerplate architecture

A boilerplate is the smallest project you can still call a SaaS: a router, a user table, a session, and one place that starts a payment. The Next.js SaaS Boilerplate is that project. It is Next.js 15 on the App Router, TypeScript, Tailwind, Prisma 6, and a Stripe Checkout route. It is not the Complete SaaS Starter Kit.

Folders that should exist on day one

src/app/page.tsx              marketing
src/app/login/page.tsx        sign in
src/app/login/actions.ts      credentials check
src/app/dashboard/page.tsx    signed-in home
src/app/pricing/page.tsx      plan list
src/app/api/stripe/checkout   starts Checkout
src/lib/auth.ts               current user
src/lib/db.ts                 Prisma client
prisma/schema.prisma

Pages stay thin. currentUser() lives in src/lib/auth.ts so a server component and a route handler share one session read. Prisma is constructed once in src/lib/db.ts. The Stripe client is a function that throws if STRIPE_SECRET_KEY is missing, which fails the request instead of sending an empty key.

Database choice

The boilerplate schema uses SQLite:

datasource db {
  provider = "sqlite"
  url      = env("DATABASE_URL")
}

DATABASE_URL is a file URL such as file:./dev.db. That is enough to run npx prisma db push and sign in locally. The schema is ordinary Prisma, so pointing provider at postgresql later does not change the User fields. Do that when you need concurrent writes. The Complete kit starts on PostgreSQL because it assumes a deployed database from the first commit.

What the boilerplate leaves out

There is a Checkout route and a plan field. There is no Customer Portal route, no webhook that downgrades a canceled subscription, and no Docker Compose file. If a customer cancels in Stripe and nothing updates plan, your dashboard will keep showing the old value. That gap is the subject of Stripe webhooks with Next.js.

Use this layout when you want to read every file in an afternoon. Move to the Complete kit, or add the Stripe Subscription Starter, when cancellation and the portal have to work.

Deploy notes

next build then next start is the Node path. On Vercel, set DATABASE_URL, AUTH_SECRET, and the Stripe keys in the project environment. SQLite on a serverless disk is a local convenience, not a production database. Switch the datasource before you invite a second user.

Want to skip the setup? The Next.js SaaS Boilerplate is the short path: App Router, accounts, dashboard, and a billing route.