SaaS Scaffolder

Key Component Patterns

Auth Config (NextAuth)

// lib/auth.ts
import { NextAuthOptions } from "next-auth"
import GoogleProvider from "next-auth/providers/google"
import { DrizzleAdapter } from "@auth/drizzle-adapter"
import { db } from "./db"

export const authOptions: NextAuthOptions = {
  adapter: DrizzleAdapter(db),
  providers: [
    GoogleProvider({
      clientId: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    }),
  ],
  callbacks: {
    session: async ({ session, user }) => ({
      ...session,
      user: {
        ...session.user,
        id: user.id,
        subscriptionStatus: user.subscriptionStatus,
      },
    }),
  },
  pages: { signIn: "/login" },
}

Database Schema (Drizzle + NeonDB)

// db/schema.ts
import { pgTable, text, timestamp, integer } from "drizzle-orm/pg-core"

export const users = pgTable("users", {
  id: text("id").primaryKey().$defaultFn(() => crypto.randomUUID()),
  name: text("name"),
  email: text("email").notNull().unique(),
  emailVerified: timestamp("emailVerified"),
  image: text("image"),
  stripeCustomerId: text("stripe_customer_id").unique(),
  stripeSubscriptionId: text("stripe_subscription_id"),
  stripePriceId: text("stripe_price_id"),
  stripeCurrentPeriodEnd: timestamp("stripe_current_period_end"),
  createdAt: timestamp("created_at").defaultNow().notNull(),
})

export const accounts = pgTable("accounts", {
  userId: text("user_id").notNull().references(() => users.id, { onDelete: "cascade" }),
  type: text("type").notNull(),
  provider: text("provider").notNull(),
  providerAccountId: text("provider_account_id").notNull(),
  refresh_token: text("refresh_token"),
  access_token: text("access_token"),
  expires_at: integer("expires_at"),
})

Stripe Checkout Route

// app/api/billing/checkout/route.ts
import { NextResponse } from "next/server"
import { getServerSession } from "next-auth"
import { authOptions } from "@/lib/auth"
import { stripe } from "@/lib/stripe"
import { db } from "@/lib/db"
import { users } from "@/db/schema"
import { eq } from "drizzle-orm"

export async function POST(req: Request) {
  const session = await getServerSession(authOptions)
  if (!session?.user) return NextResponse.json({ error: "Unauthorized" }, { status: 401 })

  const { priceId } = await req.json()
  const [user] = await db.select().from(users).where(eq(users.id, session.user.id))

  let customerId = user.stripeCustomerId
  if (!customerId) {
    const customer = await stripe.customers.create({ email: session.user.email! })
    customerId = customer.id
    await db.update(users).set({ stripeCustomerId: customerId }).where(eq(users.id, user.id))
  }

  const checkoutSession = await stripe.checkout.sessions.create({
    customer: customerId,
    mode: "subscription",
    payment_method_types: ["card"],
    line_items: [{ price: priceId, quantity: 1 }],
    success_url: `${process.env.NEXT_PUBLIC_APP_URL}/dashboard?upgraded=true`,
    cancel_url: `${process.env.NEXT_PUBLIC_APP_URL}/pricing`,
    subscription_data: { trial_period_days: 14 },
  })

  return NextResponse.json({ url: checkoutSession.url })
}

Middleware

// middleware.ts
import { withAuth } from "next-auth/middleware"
import { NextResponse } from "next/server"

export default withAuth(
  function middleware(req) {
    const token = req.nextauth.token
    if (req.nextUrl.pathname.startsWith("/dashboard") && !token) {
      return NextResponse.redirect(new URL("/login", req.url))
    }
  },
  { callbacks: { authorized: ({ token }) => !!token } }
)

export const config = {
  matcher: ["/dashboard/:path*", "/settings/:path*", "/billing/:path*"],
}

Environment Variables Template

# .env.example
NEXT_PUBLIC_APP_URL=http://localhost:3000
DATABASE_URL=postgresql://user:[email protected]/neondb?sslmode=require
NEXTAUTH_SECRET=generate-with-openssl-rand-base64-32
NEXTAUTH_URL=http://localhost:3000
GOOGLE_CLIENT_ID=
GOOGLE_CLIENT_SECRET=
STRIPE_SECRET_KEY=sk_test_...
STRIPE_WEBHOOK_SECRET=whsec_...
NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY=pk_test_...
STRIPE_PRO_PRICE_ID=price_...

Scaffold Checklist

The following phases must be completed in order. Validate at the end of each phase before proceeding.

Phase 1 — Foundation

• 1. Next.js initialized with TypeScript and App Router
• 2. Tailwind CSS configured with custom theme tokens
• 3. shadcn/ui installed and configured
• 4. ESLint + Prettier configured
• 5. .env.example created with all required variables

✅ Validate: Run npm run build — no TypeScript or lint errors should appear.
🔧 If build fails: Check tsconfig.json paths and that all shadcn/ui peer dependencies are installed.

Phase 2 — Database

• 6. Drizzle ORM installed and configured
• 7. Schema written (users, accounts, sessions, verification_tokens)
• 8. Initial migration generated and applied
• 9. DB client singleton exported from lib/db.ts
• 10. DB connection tested in local environment

✅ Validate: Run a simple db.select().from(users) in a test script — it should return an empty array without throwing.
🔧 If DB connection fails: Verify DATABASE_URL format includes ?sslmode=require for NeonDB/Supabase. Check that the migration has been applied with drizzle-kit push (dev) or drizzle-kit migrate (prod).

Phase 3 — Authentication

• 11. Auth provider installed (NextAuth / Clerk / Supabase)
• 12. OAuth provider configured (Google / GitHub)
• 13. Auth API route created
• 14. Session callback adds user ID and subscription status
• 15. Middleware protects dashboard routes
• 16. Login and register pages built with error states

✅ Validate: Sign in via OAuth, confirm session user has id and subscriptionStatus. Attempt to access /dashboard without a session — you should be redirected to /login.
🔧 If sign-out loops occur in production: Ensure NEXTAUTH_SECRET is set and consistent across deployments. Add declare module "next-auth" to extend session types if TypeScript errors appear.

Phase 4 — Payments

• 17. Stripe client initialized with TypeScript types
• 18. Checkout session route created
• 19. Customer portal route created
• 20. Stripe webhook handler with signature verification
• 21. Webhook updates user subscription status in DB idempotently

✅ Validate: Complete a Stripe test checkout using a 4242 4242 4242 4242 card. Confirm stripeSubscriptionId is written to the DB. Replay the checkout.session.completed webhook event and confirm idempotency (no duplicate DB writes).
🔧 If webhook signature fails: Use stripe listen --forward-to localhost:3000/api/webhooks/stripe locally — never hardcode the raw webhook secret. Verify STRIPE_WEBHOOK_SECRET matches the listener output.

Phase 5 — UI

• 22. Landing page with hero, features, pricing sections
• 23. Dashboard layout with sidebar and responsive header
• 24. Billing page showing current plan and upgrade options
• 25. Settings page with profile update form and success states

✅ Validate: Run npm run build for a final production build check. Navigate all routes manually and confirm no broken layouts, missing session data, or hydration errors.

Reference Files

For additional guidance, generate the following companion reference files alongside the scaffold:

• CUSTOMIZATION.md — Auth providers, database options, ORM alternatives, payment providers, UI themes, and billing models (per-seat, flat-rate, usage-based).
• PITFALLS.md — Common failure modes: missing NEXTAUTH_SECRET, webhook secret mismatches, Edge runtime conflicts with Drizzle, unextended session types, and migration strategy differences between dev and prod.
• BEST_PRACTICES.md — Stripe singleton pattern, server actions for form mutations, idempotent webhook handlers, Suspense boundaries for async dashboard data, server-side feature gating via stripeCurrentPeriodEnd, and rate limiting on auth routes with Upstash Redis + @upstash/ratelimit.