How I Built Automated Product Delivery in 2 Hours (Stripe + Netlify + Resend)

Customer clicks "Buy" 
  → Stripe Checkout (hosted payment page)
  → Payment succeeds
  → Stripe fires webhook → Netlify Function
  → Function identifies product by Stripe product ID
  → Resend sends branded email with download links
  → Customer gets their files in < 60 seconds

https://yourdomain.com/thanks?product=your-product-name

const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);

// Map your Stripe product IDs to delivery info
const PRODUCTS = {
  'prod_YOUR_PRODUCT_ID': {
    name: 'Your Product Name',
    downloads: [
      {
        label: 'Download Now',
        url: 'https://yourdomain.com/downloads/your-file.zip',
      },
    ],
  },
  // Add more products here
};

async function sendDeliveryEmail(customerEmail, customerName, product) {
  const firstName = customerName ? customerName.split(' ')[0] : 'there';

  const downloadButtons = product.downloads.map(d =>
    `<a href="${d.url}" style="background:#000;color:#fff;padding:12px 24px;border-radius:6px;text-decoration:none;font-weight:bold;">${d.label} →</a>`
  ).join('
');

  await fetch('https://api.resend.com/emails', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.RESEND_API_KEY}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      from: 'You <hello@yourdomain.com>',
      to: [customerEmail],
      subject: `Your download is ready: ${product.name}`,
      html: `
        <div style="font-family:sans-serif;max-width:500px;margin:0 auto;padding:40px;">
          <h1>You're in. 🚀</h1>
          <p>Hey ${firstName}, your <strong>${product.name}</strong> is ready.</p>
          <div style="margin:24px 0;">${downloadButtons}</div>
          <p style="color:#666;">Questions? Reply to this email.</p>
        </div>
      `,
    }),
  });
}

exports.handler = async (event) => {
  if (event.httpMethod !== 'POST') {
    return { statusCode: 405, body: 'Method Not Allowed' };
  }

  const sig = event.headers['stripe-signature'];

  let webhookEvent;
  try {
    webhookEvent = stripe.webhooks.constructEvent(
      event.body,
      sig,
      process.env.STRIPE_WEBHOOK_SECRET
    );
  } catch (err) {
    return { statusCode: 400, body: `Webhook error: ${err.message}` };
  }

  if (webhookEvent.type === 'checkout.session.completed') {
    const session = webhookEvent.data.object;
    const customerEmail = session.customer_details?.email;
    const customerName = session.customer_details?.name;

    // Get line items to identify which product was purchased
    const lineItems = await stripe.checkout.sessions.listLineItems(session.id, {
      expand: ['data.price.product'],
    });

    for (const item of lineItems.data) {
      const productId = typeof item.price?.product === 'object'
        ? item.price.product.id
        : item.price?.product;

      const product = PRODUCTS[productId];

      if (product && customerEmail) {
        await sendDeliveryEmail(customerEmail, customerName, product);
      }
    }
  }

  return { statusCode: 200, body: JSON.stringify({ received: true }) };
};

STRIPE_SECRET_KEY=sk_live_xxx
STRIPE_WEBHOOK_SECRET=whsec_xxx
RESEND_API_KEY=re_xxx