Stripe Integration

Stripe Integration

This skill ensures Stripe payment integration is implemented correctly the first time, following best practices for security, reliability, and user experience.

When to Use This Skill

Use this skill when:

• Adding Stripe to a new application
• Implementing subscription billing
• Setting up payment processing
• Configuring webhooks
• Managing customer lifecycle
• Handling refunds or disputes
• Implementing checkout flows

Core Principles

Security First:

• Never expose secret keys client-side
• Always use HTTPS in production
• Validate webhook signatures
• Use Stripe's client-side libraries for card handling

Idempotency:

• Use idempotency keys for API requests
• Handle duplicate webhook events
• Design for retry-safety

User Experience:

• Clear error messages
• Loading states during payment
• Success/failure feedback
• Email confirmations

Implementation Workflow

1. Environment Setup

Required Credentials:

STRIPE_PUBLISHABLE_KEY_TEST=pk_test_...
STRIPE_SECRET_KEY_TEST=sk_test_...
STRIPE_WEBHOOK_SECRET_TEST=whsec_...

STRIPE_PUBLISHABLE_KEY_PROD=pk_live_...
STRIPE_SECRET_KEY_PROD=sk_live_...
STRIPE_WEBHOOK_SECRET_PROD=whsec_...

Never Commit:

• Add to .env or secrets manager
• Use .gitignore for env files
• Different keys for dev/staging/prod

Installation:

# Node.js
npm install stripe @stripe/stripe-js

# Python
pip install stripe

2. Basic Payment Flow

Client-Side (React example):

import { loadStripe } from '@stripe/stripe-js';
import { Elements, CardElement, useStripe, useElements } from '@stripe/react-stripe-js';

const stripePromise = loadStripe(process.env.NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY);

function CheckoutForm() {
  const stripe = useStripe();
  const elements = useElements();

  const handleSubmit = async (event) => {
    event.preventDefault();
    
    if (!stripe || !elements) return;

    // Create payment intent on backend first
    const { clientSecret } = await fetch('/api/create-payment-intent', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ amount: 5000 }) // $50.00
    }).then(r => r.json());

    // Confirm payment on client
    const { error, paymentIntent } = await stripe.confirmCardPayment(
      clientSecret,
      {
        payment_method: {
          card: elements.getElement(CardElement),
          billing_details: {
            name: 'Customer Name',
            email: 'customer@example.com'
          }
        }
      }
    );

    if (error) {
      console.error(error.message);
    } else if (paymentIntent.status === 'succeeded') {
      // Payment successful
      console.log('Payment succeeded!');
    }
  };

  return (
    <form
      <CardElement />
      <button type="submit" disabled={!stripe}>
        Pay
      </button>
    </form>
  );
}

Server-Side (Node.js example):

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

app.post('/api/create-payment-intent', async (req, res) => {
  try {
    const { amount } = req.body;

    const paymentIntent = await stripe.paymentIntents.create({
      amount: amount,
      currency: 'usd',
      automatic_payment_methods: {
        enabled: true,
      },
      metadata: {
        userId: req.user.id, // Track in your DB
        orderId: req.body.orderId
      }
    });

    res.json({ clientSecret: paymentIntent.client_secret });
  } catch (error) {
    res.status(500).json({ error: error.message });
  }
});

3. Subscription Implementation

Create Subscription:

// Server-side
async function createSubscription(customerId, priceId) {
  const subscription = await stripe.subscriptions.create({
    customer: customerId,
    items: [{ price: priceId }],
    payment_behavior: 'default_incomplete',
    payment_settings: {
      save_default_payment_method: 'on_subscription'
    },
    expand: ['latest_invoice.payment_intent']
  });

  return {
    subscriptionId: subscription.id,
    clientSecret: subscription.latest_invoice.payment_intent.client_secret
  };
}

Handle Subscription Lifecycle:

• Customer signs up → create customer + subscription
• Payment succeeds → activate features
• Payment fails → notify customer, retry
• Cancellation requested → process at period_end
• Renewal → webhook confirms payment

4. Webhook Configuration

CRITICAL: Webhooks are how Stripe notifies you of events. Must be implemented correctly.

Endpoint Setup:

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

app.post('/webhook', express.raw({type: 'application/json'}), async (req, res) => {
  const sig = req.headers['stripe-signature'];
  let event;

  try {
    // Verify webhook signature
    event = stripe.webhooks.constructEvent(
      req.body,
      sig,
      process.env.STRIPE_WEBHOOK_SECRET
    );
  } catch (err) {
    console.log(`Webhook signature verification failed: ${err.message}`);
    return res.status(400).send(`Webhook Error: ${err.message}`);
  }

  // Handle the event
  switch (event.type) {
    case 'payment_intent.succeeded':
      const paymentIntent = event.data.object;
      await handlePaymentSuccess(paymentIntent);
      break;

    case 'payment_intent.payment_failed':
      const failedPayment = event.data.object;
      await handlePaymentFailure(failedPayment);
      break;

    case 'customer.subscription.created':
      const subscription = event.data.object;
      await handleSubscriptionCreated(subscription);
      break;

    case 'customer.subscription.updated':
      const updatedSub = event.data.object;
      await handleSubscriptionUpdated(updatedSub);
      break;

    case 'customer.subscription.deleted':
      const deletedSub = event.data.object;
      await handleSubscriptionCanceled(deletedSub);
      break;

    case 'invoice.payment_succeeded':
      const invoice = event.data.object;
      await handleInvoicePaymentSucceeded(invoice);
      break;

    case 'invoice.payment_failed':
      const failedInvoice = event.data.object;
      await handleInvoicePaymentFailed(failedInvoice);
      break;

    default:
      console.log(`Unhandled event type ${event.type}`);
  }

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

Essential Events to Handle:

1. payment_intent.succeeded - One-time payment successful
2. payment_intent.payment_failed - Payment failed
3. customer.subscription.created - New subscription
4. customer.subscription.updated - Subscription changed
5. customer.subscription.deleted - Subscription canceled
6. invoice.payment_succeeded - Recurring payment successful
7. invoice.payment_failed - Recurring payment failed

5. Customer Management

Create Customer:

const customer = await stripe.customers.create({
  email: user.email,
  name: user.name,
  metadata: {
    userId: user.id
  }
});

// Store customer.id in your database
await db.users.update(user.id, {
  stripeCustomerId: customer.id
});

Attach Payment Method:

const paymentMethod = await stripe.paymentMethods.attach(
  pm_id,
  { customer: customerId }
);

await stripe.customers.update(customerId, {
  invoice_settings: {
    default_payment_method: pm_id
  }
});

6. Testing

Test Mode:

• Use test keys (pk_test_, sk_test_)
• Test card numbers:
  • Success: 4242 4242 4242 4242
  • Declined: 4000 0000 0000 0002
  • 3D Secure: 4000 0027 6000 3184
• Use stripe CLI for webhook testing:

  stripe listen --forward-to localhost:3000/webhook
  stripe trigger payment_intent.succeeded
  

Webhook Testing:

# Install Stripe CLI
brew install stripe/stripe-cli/stripe

# Login
stripe login

# Forward webhooks to local server
stripe listen --forward-to localhost:3000/webhook

# Trigger events manually
stripe trigger customer.subscription.created

7. Error Handling

Common Errors to Handle:

try {
  const charge = await stripe.charges.create({...});
} catch (error) {
  switch (error.type) {
    case 'StripeCardError':
      // Card was declined
      console.log('Card declined:', error.message);
      break;
    case 'StripeInvalidRequestError':
      // Invalid parameters
      console.log('Invalid request:', error.message);
      break;
    case 'StripeAPIError':
      // Stripe API error
      console.log('API error:', error.message);
      break;
    case 'StripeConnectionError':
      // Network error
      console.log('Network error');
      break;
    case 'StripeAuthenticationError':
      // Authentication error
      console.log('Auth error');
      break;
    default:
      console.log('Unknown error:', error);
  }
}

Checklist for Production

Before going live:

• Using live API keys (pk_live_, sk_live_)
• HTTPS enabled everywhere
• Webhook endpoint configured in Stripe Dashboard
• Webhook signature verification implemented
• All critical events handled
• Idempotency keys on API calls
• Customer creation linked to user accounts
• Error handling for all payment flows
• Email notifications setup
• Refund process documented
• Tested with real test cards
• Webhook events tested via CLI
• Subscription renewal flow tested
• Cancellation flow tested
• Failed payment retry logic
• Security review completed

Common Patterns

Subscription Tiers

const plans = {
  basic: 'price_basic123',
  pro: 'price_pro456',
  enterprise: 'price_enterprise789'
};

function subscribeToPlan(customerId, tier) {
  return stripe.subscriptions.create({
    customer: customerId,
    items: [{ price: plans[tier] }]
  });
}

Usage-Based Billing

// Record usage
await stripe.subscriptionItems.createUsageRecord(
  subscriptionItemId,
  {
    quantity: 100,
    timestamp: Math.floor(Date.now() / 1000),
    action: 'increment'
  }
);

Prorated Upgrades

await stripe.subscriptions.update(subscriptionId, {
  items: [{
    id: subscriptionItemId,
    price: newPriceId
  }],
  proration_behavior: 'create_prorations'
});

Resources

Official Docs:

• https://stripe.com/docs
• https://stripe.com/docs/webhooks
• https://stripe.com/docs/billing/subscriptions/overview

Testing:

• https://stripe.com/docs/testing
• https://stripe.com/docs/cli

Security:

• https://stripe.com/docs/security/guide
• https://stripe.com/docs/keys

Tips

1. Start Simple: Get basic payments working before subscriptions
2. Use Stripe Checkout: Hosted page handles complex flows
3. Test Webhooks Thoroughly: Use CLI to simulate all events
4. Log Everything: Track payment intents, events in your DB
5. Handle Failures Gracefully: Retry logic, user notifications
6. Keep Test/Prod Separate: Never mix keys or environments
7. Monitor Stripe Dashboard: Check for errors and disputes
8. Read Stripe Docs: They're excellent and comprehensive