SaaS auth and billing code snippet pack

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SaaS Auth & Billing Code Snippet Pack — Free Preview

Production-ready auth + Paddle/Stripe billing code for Node/TypeScript SaaS apps. Below is one complete, working snippet from the pack — yours to use right now — plus the full table of contents so you can see everything the paid version includes.

✅ Free sample: Verify a billing webhook signature (the step most people get wrong)

Webhook handlers are the #1 source of billing bugs because developers trust the payload without verifying it came from the provider. Here's a real, working signature-verification middleware for Stripe that you can drop into an Express app today.

// webhookVerify.ts
import type { Request, Response, NextFunction } from "express";
import Stripe from "stripe";

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

const WEBHOOK_SECRET = process.env.STRIPE_WEBHOOK_SECRET!;

/**
 * Mount with express.raw({ type: "application/json" }) BEFORE express.json().
 * Stripe signs the raw bytes — parsed JSON will fail verification.
 */
export function verifyStripeWebhook(
  req: Request,
  res: Response,
  next: NextFunction
) {
  const sig = req.headers["stripe-signature"];
  if (!sig) return res.status(400).send("Missing signature header");

  try {
    const event = stripe.webhooks.constructEvent(
      req.body,            // raw Buffer, not parsed JSON
      sig,
      WEBHOOK_SECRET
    );
    // Attach the verified event for the next handler.
    (req as any).stripeEvent = event;
    next();
  } catch (err) {
    // Signature mismatch, replay, or tampering — reject.
    return res
      .status(400)
      .send(`Webhook verification failed: ${(err as Error).message}`);
  }
}

// route wiring (the part the docs gloss over)
import express from "express";
import { verifyStripeWebhook } from "./webhookVerify";

const app = express();

// IMPORTANT: raw body ONLY on the webhook route, JSON everywhere else.
app.post(
  "/webhooks/stripe",
  express.raw({ type: "application/json" }),
  verifyStripeWebhook,
  (req, res) => {
    const event = (req as any).stripeEvent;
    switch (event.type) {
      case "checkout.session.completed":
        // grant access / provision the account
        break;
      case "customer.subscription.deleted":
        // revoke access
        break;
    }
    res.json({ received: true });
  }
);

app.use(express.json()); // all other routes

Why this matters: the most common failure is mounting express.json() globally, which consumes the raw body and makes signature verification fail every time. Scoping express.raw() to just the webhook route fixes it. This snippet alone saves the afternoon most people lose to "signature verification failed" errors.

📦 What's in the full pack ($99)

The free sample above is 1 of 40+ snippets. The complete pack includes:

1. Authentication

• Email/password signup with Argon2 hashing
• Session vs. JWT — both implementations, with tradeoff notes
• Refresh-token rotation + revocation
• Password reset flow (token generation, expiry, single-use)
• Email verification flow
• OAuth (Google + GitHub) handlers
• Rate limiting for login & reset endpoints

2. Authorization

• Role-based access control (RBAC) middleware
• Per-resource ownership checks
• API-key generation & validation for programmatic access

3. Billing — Stripe

• Checkout session creation
• Webhook handler (full event router)
• Subscription lifecycle: create, upgrade/downgrade, cancel, reactivate
• Proration & trial handling
• Customer portal redirect

4. Billing — Paddle

• Paddle Billing checkout + webhook verification
• Subscription mapping to your user records

5. Entitlements

• Feature-flag / plan-gating helper
• Usage-metering pattern for metered billing
• Grace-period & dunning state machine

6. Hardening & Glue

• Idempotency keys for billing operations
• Webhook replay protection
• Environment/config schema (typed, validated)
• Test fixtures & a mock provider for local dev

Every snippet is TypeScript-first, commented, and framework-agnostic where possible (Express examples, adaptable to Fastify/Next.js route handlers).

Note on what this is: a code reference pack to speed up your own implementation. It is not a hosted service, and it doesn't replace reading your payment provider's official docs or doing your own security and compliance review for your jurisdiction.

👉 Get the complete pack

The free snippet above is fully functional. The $99 pack gives you the other 39+ snippets — the entire auth + billing layer — so you ship in days instead of weeks.

[Buy the full SaaS Auth & Billing Code Snippet Pack — $99 →]

One-time purchase. Instant download. Use it in unlimited projects you own.