Stripe

Client Setup

// Server-side (Node.js)
const stripe = require('stripe')(process.env.STRIPE_SECRET_KEY);
// or
import Stripe from 'stripe';
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY);

Checkout Sessions

One-Time Payment

const session = await stripe.checkout.sessions.create({
  mode: 'payment',
  line_items: [
    {
      price: 'price_xxxxx', // or use price_data for inline
      quantity: 1,
    },
  ],
  success_url: `${YOUR_DOMAIN}/success?session_id={CHECKOUT_SESSION_ID}`,
  cancel_url: `${YOUR_DOMAIN}/cancel`,
  metadata: { userId: '123' }, // passed to webhook
});

// Redirect client to session.url
res.redirect(303, session.url);

Subscription

const session = await stripe.checkout.sessions.create({
  mode: 'subscription',
  line_items: [{ price: 'price_monthly_xxxxx', quantity: 1 }],
  success_url: `${YOUR_DOMAIN}/success?session_id={CHECKOUT_SESSION_ID}`,
  cancel_url: `${YOUR_DOMAIN}/cancel`,
  customer_email: '[email protected]', // or customer: 'cus_xxxxx'
});

Inline Price (no pre-created price)

const session = await stripe.checkout.sessions.create({
  mode: 'payment',
  line_items: [{
    price_data: {
      currency: 'usd',
      product_data: { name: 'Sway Score Lookup' },
      unit_amount: 99, // $0.99 in cents
    },
    quantity: 1,
  }],
  success_url: `${YOUR_DOMAIN}/success`,
  cancel_url: `${YOUR_DOMAIN}/cancel`,
});

Webhooks

Endpoint Handler (Node.js / Serverless)

import Stripe from 'stripe';

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY);
const endpointSecret = process.env.STRIPE_WEBHOOK_SECRET;

// CRITICAL: Use raw body, not parsed JSON
export const config = { api: { bodyParser: false } }; // Next.js
// For Vercel serverless: read raw body from request

export default async function handler(req, res) {
  const sig = req.headers['stripe-signature'];
  const rawBody = await getRawBody(req); // or req.body if raw

  let event;
  try {
    event = stripe.webhooks.constructEvent(rawBody, sig, endpointSecret);
  } catch (err) {
    console.error('Webhook signature verification failed:', err.message);
    return res.status(400).send(`Webhook Error: ${err.message}`);
  }

  switch (event.type) {
    case 'checkout.session.completed':
      const session = event.data.object;
      // Fulfill order, update DB
      await handleCheckoutComplete(session);
      break;
    case 'invoice.paid':
      // Subscription payment succeeded
      break;
    case 'invoice.payment_failed':
      // Subscription payment failed
      break;
    case 'customer.subscription.updated':
      // Plan change, cancellation, etc.
      break;
    case 'customer.subscription.deleted':
      // Subscription ended
      break;
    default:
      console.log(`Unhandled event: ${event.type}`);
  }

  res.json({ received: true });
}

Common Events

Retry Behavior

• Live mode: Retries up to 3 days with exponential backoff
• Sandbox: Retries 3 times over a few hours
• Return 2xx quickly — do heavy processing async
• Log event.id to deduplicate retries

Products & Prices

// Create a product
const product = await stripe.products.create({
  name: 'Sway Score Lookup',
  description: 'One-time influence score check',
});

// Create a one-time price
const price = await stripe.prices.create({
  product: product.id,
  unit_amount: 99,     // cents
  currency: 'usd',
});

// Create a recurring price
const monthlyPrice = await stripe.prices.create({
  product: product.id,
  unit_amount: 999,
  currency: 'usd',
  recurring: { interval: 'month' },
});

Sandbox vs Production: Price IDs differ between modes. Use environment variables:

STRIPE_PRICE_LOOKUP=price_test_xxx    # sandbox
STRIPE_PRICE_LOOKUP=price_live_xxx    # production

Customer Management

// Create customer
const customer = await stripe.customers.create({
  email: '[email protected]',
  metadata: { userId: '123' },
});

// Retrieve
const customer = await stripe.customers.retrieve('cus_xxxxx');

// List
const customers = await stripe.customers.list({ limit: 10 });

Subscriptions

// Create (if not using Checkout)
const subscription = await stripe.subscriptions.create({
  customer: 'cus_xxxxx',
  items: [{ price: 'price_xxxxx' }],
  trial_period_days: 14,
});

// Cancel at period end
await stripe.subscriptions.update('sub_xxxxx', {
  cancel_at_period_end: true,
});

// Cancel immediately
await stripe.subscriptions.cancel('sub_xxxxx');

// Change plan
await stripe.subscriptions.update('sub_xxxxx', {
  items: [{
    id: 'si_xxxxx', // subscription item ID
    price: 'price_new_xxxxx',
  }],
  proration_behavior: 'create_prorations',
});

Stripe CLI

# Install (macOS)
brew install stripe/stripe-cli/stripe

# Login
stripe login

# Listen for webhooks locally
stripe listen --forward-to localhost:3000/api/webhooks/stripe

# Trigger test events
stripe trigger checkout.session.completed
stripe trigger payment_intent.succeeded
stripe trigger customer.subscription.created

# View recent events
stripe events list --limit 10

# View logs
stripe logs tail

# Create test resources
stripe products create --name="Test Product"
stripe prices create --product=prod_xxx --unit-amount=999 --currency=usd

Testing

Test Card Numbers

Use any future expiry date, any 3-digit CVC, any postal code.

Environment Variables

STRIPE_SECRET_KEY=sk_test_...          # Server-side only
STRIPE_PUBLISHABLE_KEY=pk_test_...     # Client-side safe
STRIPE_WEBHOOK_SECRET=whsec_...        # For webhook verification

Common Gotchas

• Raw body required: Webhook signature verification needs the raw request body, not parsed JSON. In Next.js: export const config = { api: { bodyParser: false } }. In Vercel serverless: read req.body as buffer.
• Idempotency keys: Use for POST requests to prevent duplicate charges: stripe.paymentIntents.create({...}, { idempotencyKey: 'unique-key' })
• Sandbox vs live: All test resources use _test_ in keys. Switch by changing API key.
• Webhook timing: Don't rely on redirect success URL for fulfillment — always use webhooks.
• Amount in cents: unit_amount: 999 = $9.99, not $999.