Payments

Payment Integration Mastery

Production-proven multi-provider payment processing with Stripe, Paddle, SePay, Polar, and Creem.io.

Platform Selection

Implementation Flow (All Providers)

1. Auth (API keys, secrets)
2. Create Products/Prices
3. Implement Checkout
4. Handle Webhooks
5. Manage Subscriptions
6. Monitor & Reconcile

Reference Navigation

Stripe

• Stripe Integration — Checkout Sessions, Payment Element, Billing Portal, Connect
• Stripe Webhooks — Event handling, signature verification, idempotency

Paddle

• Paddle Integration — MoR model, overlay/inline checkout, subscription lifecycle
• Paddle Webhooks — SHA256 verification, event types, Retain

Vietnam & Others

• SePay VietQR — Vietnamese bank integration, QR code payments, webhook setup
• Polar & Creem — Global SaaS billing, software licensing, benefits delivery

Architecture

• Multi-Provider Patterns — Unified order management, provider abstraction, currency handling

Quick Start (Stripe)

// Server: Create checkout session
import Stripe from 'stripe'
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!)

const session = await stripe.checkout.sessions.create({
  line_items: [{
    price: 'price_xxx',
    quantity: 1
  }],
  mode: 'subscription',
  success_url: 'https://myapp.com/success?session_id={CHECKOUT_SESSION_ID}',
  cancel_url: 'https://myapp.com/cancel'
})

// Redirect to session.url

// Webhook handler
import { buffer } from 'micro'

export async function POST(req: Request) {
  const body = await req.text()
  const sig = req.headers.get('stripe-signature')!
  
  const event = stripe.webhooks.constructEvent(body, sig, process.env.STRIPE_WEBHOOK_SECRET!)
  
  switch (event.type) {
    case 'checkout.session.completed':
      await handleCheckoutComplete(event.data.object)
      break
    case 'invoice.payment_succeeded':
      await handlePaymentSuccess(event.data.object)
      break
    case 'customer.subscription.deleted':
      await handleSubscriptionCancelled(event.data.object)
      break
  }
  
  return new Response('ok')
}

Best Practices

1. Always verify webhook signatures — Never trust unverified webhooks
2. Idempotent webhook handlers — Process each event exactly once
3. Store provider IDs — Map Stripe/Paddle IDs to your internal IDs
4. Handle edge cases — Failed payments, disputed charges, refunds
5. Test with CLI tools — stripe listen --forward-to localhost:3000/webhook
6. Use MoR for global — Paddle/Creem handle tax compliance for you

Related Skills