Introduction

The old SaaS playbook is broken. Bolting features onto a fragile architecture with vendor-locked identity and messy billing logic is a recipe for technical debt. It's time to stop patching and start building on a solid foundation.

This guide provides that foundation. A clean, modular, and production-ready stack for builders who value ownership, control, and execution. We'll integrate Better Auth for identity, Supabase for a managed Postgres database, Drizzle for a lightweight ORM, and Stripe for automated billing—all unified by the power of the Next.js App Router.

This isn't an incremental improvement. It's a transformational shift in how you build.

The Foundation: A Modern Architecture

Clean separation of concerns isn't a "nice-to-have." It's everything. This stack is designed for clarity and durability.

• Next.js App Router: The core for routes, middleware, and server components. We leverage the modern Next.js paradigm for a seamless developer experience.
• Better Auth + Drizzle on Supabase: The single source of truth for identity. We own our user data on a production-grade Postgres instance, accessed via a type-safe, lightweight adapter. No provider-specific JWTs, no lock-in.
• Stripe: The automated billing engine. We offload PCI scope, SCA/3DS, and subscription management to Stripe’s hosted Checkout and billing portal, integrated cleanly via webhooks.

This isn't just a collection of tools. It's a deliberate architecture that puts the builder in control.

Prerequisites

You're a builder. You probably have this ready.

• Node.js LTS
• A Next.js 14/15 project
• A Supabase project with Postgres
• A Stripe account (test mode is fine)
• Stripe CLI for local webhook testing

1. Laying the Groundwork

First, we assemble the core components.

Install Dependencies

Pull in the necessary SDKs and adapters. One command.

npm install better-auth pg drizzle-orm drizzle-kit stripe @stripe/stripe-js

Configure Your Environment

Create a .env.local file. These keys are non-negotiable. Keep them secure.

# Better Auth: Secret for signing sessions
BETTER_AUTH_SECRET="your_long_random_secret"
BETTER_AUTH_URL="http://localhost:3000"

# Database: Supabase Postgres connection string
DATABASE_URL="postgresql://USER:PASSWORD@HOST:PORT/postgres?sslmode=require"

# Stripe: API keys and webhook secret for signature verification
STRIPE_SECRET_KEY="sk_test_xxx"
NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY="pk_test_xxx"
STRIPE_WEBHOOK_SECRET="whsec_xxx" # From Stripe CLI or dashboard

2. The Database: Your Single Source of Truth

We build on Supabase Postgres for its reliability and scalability. Drizzle gives us a type-safe, high-performance way to talk to it.

Create the Drizzle Client

Create a pooled connection to Supabase. This is your gateway to the database.

// lib/db.ts
import { Pool } from "pg";
import { drizzle } from "drizzle-orm/node-postgres";
import * as schema from "@/drizzle/schema";

export const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  ssl: { rejectUnauthorized: false }, // Adjust for production CAs
  max: 10,
});

export const db = drizzle(pool, { schema });

Generate and Run Migrations

Use Drizzle Kit or the Better Auth CLI to generate the SQL for the auth tables. Apply it via the Supabase SQL Editor. Your foundation needs a schema.

3. Identity: The Ownership Layer

Better Auth gives you full control over your user model and authentication logic.

Configure Better Auth

In lib/auth.ts, we wire Better Auth to use our Drizzle client and define our authentication rules.

// lib/auth.ts
import { betterAuth } from "better-auth";
import { drizzleAdapter } from "better-auth/adapters/drizzle";
import { db } from "@/lib/db";
import Stripe from "stripe";
import { stripePlugin } from "better-auth/plugins/stripe";

// Your email sending implementation (Resend, SES, etc.)
async function sendEmail({ to, subject, html }: { to: string; subject:string; html: string }) {
  console.log(`Sending email to ${to} with subject: ${subject}`);
}

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, { apiVersion: "2024-06-20" });

export const auth = betterAuth({
  database: drizzleAdapter(db, { provider: "pg" }),

  emailAndPassword: {
    enabled: true,
    // Define strong password rules
  },

  email: {
    sendVerificationEmail: async ({ email, token }) => { /* ... */ },
    sendPasswordResetEmail: async ({ email, token }) => { /* ... */ },
    requireVerification: true,
  },

  session: {
    strategy: "database",
    maxAge: 14 * 24 * 60 * 60 * 1000, // 14 days
  },

  plugins: [
    stripePlugin({
      stripeClient: stripe,
      stripeWebhookSecret: process.env.STRIPE_WEBHOOK_SECRET!,
      createCustomerOnSignUp: true,
      subscriptions: {
        enabled: true,
        plans: [
          { name: "basic", priceId: "price_xxx_basic" },
          { name: "pro",   priceId: "price_xxx_pro" },
        ],
        requireEmailVerification: true,
      },
    }),
  ],
});```

# 4. The Framework: Tying It All Together
With the core configured, we integrate it seamlessly into the Next.js App Router.

### Expose the Auth API Handler
A single catch-all route handles all authentication endpoints (`/signin`, `/signout`, `/verify-email`, etc.). Clean.
```typescript
// app/api/auth/[...all]/route.ts
import { auth } from "@/lib/auth";
import { toNextJsHandler } from "better-auth/next-js";

export const { GET, POST } = toNextJsHandler(auth.handler);

Protect routes with middleware

Guard your protected routes. Unauthenticated users are redirected to sign-in. This is fundamental.

// middleware.ts
import { NextRequest, NextResponse } from "next/server";
import { auth } from "@/lib/auth";

export async function middleware(req: NextRequest) {
  const publicPaths = ["/signin", "/signup"]; // Add other public paths
  const path = req.nextUrl.pathname;
  if (publicPaths.includes(path) || path.startsWith("/api/")) {
    return NextResponse.next();
  }

  const session = await auth.api.getSession({ headers: req.headers });
  if (!session) {
    const signinUrl = new URL("/signin", req.url);
    signinUrl.searchParams.set("callbackUrl", path);
    return NextResponse.redirect(signinUrl);
  }
  return NextResponse.next();
}

export const config = { matcher: ["/((?!_next/static|_next/image|favicon.ico).*)"] };

Use Sessions in Server Components

Fetch session data directly on the server. No client-side roundtrips needed.

// app/dashboard/page.tsx
import { auth } from "@/lib/auth";
import { headers } from "next/headers";
import { redirect } from "next/navigation";

export default async function DashboardPage() {
  const session = await auth.api.getSession({ headers: headers() });
  if (!session) redirect("/signin");

  // Your protected page logic here
  return <h1>Welcome, {session.user.email}</h1>;
}

4. The Engine: Automated Billing with Stripe

The Stripe plugin handles the complexity of creating customers, managing checkout, and listening for webhook events. You focus on your product.

Trigger a Subscription

From your pricing page, a client-side action creates a Checkout Session and redirects the user to Stripe.

// Your client-side action
import { createAuthClient } from "better-auth/react";
const authClient = createAuthClient();

export async function startSubscription(plan: "basic" | "pro") {
  const { error } = await authClient.subscription.upgrade({
    plan,
    successUrl: `${window.location.origin}/dashboard`,
    cancelUrl: `${window.location.origin}/pricing`,
  });
  if (error) {
    // Handle error gracefully
    alert(error.message);
  }
}

Handle with Webhooks

Point your Stripe webhook to /api/auth/stripe. The plugin handles signature verification and updates your database automatically when a subscription is created or changed. Use the Stripe CLI for local testing:

stripe listen --forward-to localhost:3000/api/auth/stripe

Manage Billing

Redirect users to the Stripe Billing Portal to manage their subscriptions, payment methods, and invoices. The plugin provides a simple action to create a portal session.

Security: Non-Negotiable Defaults

• CSRF Protection: Handled out of the box by Better Auth for all auth-related POST requests.
• Webhook Verification: The Stripe plugin validates webhook signatures. Rejects any request that doesn't match.
• Secret Management: Keep BETTER_AUTH_SECRET and STRIPE_SECRET_KEY server-side. Never expose them to the client.

Wrap Up

This is a blueprint - A robust, scalable, and modern foundation for building a real SaaS business. It’s designed to give you, the builder, maximum control and velocity by automating the tedious and abstracting the complex. Stop wrestling with legacy auth providers and messy billing code. Build on a solid foundation. Expand. Enhance. Then execute.