Payment Integration

Production-proven payment processing with SePay (Vietnamese banks), Polar (global SaaS), Stripe (global infrastructure), Paddle (MoR subscriptions), and Creem.io (MoR + licensing).

When to Use

• Payment gateway integration (checkout, processing)
• Subscription management (trials, upgrades, billing)
• Webhook handling (notifications, idempotency)
• QR code payments (VietQR, NAPAS)
• Software licensing (device activation)
• Multi-provider order management
• Revenue splits and commissions

Platform Selection

Platform	Best For
SePay	Vietnamese market, VND, bank transfers, VietQR
Polar	Global SaaS, subscriptions, automated benefits (GitHub/Discord)
Stripe	Enterprise payments, Connect platforms, custom checkout
Paddle	MoR subscriptions, global tax compliance, churn prevention
Creem.io	MoR + licensing, revenue splits, no-code checkout

Quick Reference

SePay

• references/sepay/overview.md - Auth, supported banks
• references/sepay/api.md - Endpoints, transactions
• references/sepay/webhooks.md - Setup, verification
• references/sepay/sdk.md - Node.js, PHP, Laravel
• references/sepay/qr-codes.md - VietQR generation
• references/sepay/best-practices.md - Production patterns

Polar

• references/polar/overview.md - Auth, MoR concept
• references/polar/products.md - Pricing models
• references/polar/checkouts.md - Checkout flows
• references/polar/subscriptions.md - Lifecycle management
• references/polar/webhooks.md - Event handling
• references/polar/benefits.md - Automated delivery
• references/polar/sdk.md - Multi-language SDKs
• references/polar/best-practices.md - Production patterns

Stripe

• references/stripe/stripe-best-practices.md - Integration design
• references/stripe/stripe-sdks.md - Server SDKs
• references/stripe/stripe-js.md - Payment Element
• references/stripe/stripe-cli.md - Local testing
• references/stripe/stripe-upgrade.md - Version upgrades
• External: https://docs.stripe.com/llms.txt

Paddle

• references/paddle/overview.md - MoR, auth, entity IDs
• references/paddle/api.md - Products, prices, transactions
• references/paddle/paddle-js.md - Checkout overlay/inline
• references/paddle/subscriptions.md - Trials, upgrades, pause
• references/paddle/webhooks.md - SHA256 verification
• references/paddle/sdk.md - Node, Python, PHP, Go
• references/paddle/best-practices.md - Production patterns
• External: https://developer.paddle.com/llms.txt

Creem.io

• references/creem/overview.md - MoR, auth, global support
• references/creem/api.md - Products, checkout sessions
• references/creem/checkouts.md - No-code links, storefronts
• references/creem/subscriptions.md - Trials, seat-based
• references/creem/licensing.md - Device activation
• references/creem/webhooks.md - Signature verification
• references/creem/sdk.md - Next.js, Better Auth
• External: https://docs.creem.io/llms.txt

Multi-Provider

• references/multi-provider-order-management-patterns.md - Unified orders, currency conversion

Scripts

• scripts/sepay-webhook-verify.js - SePay webhook verification
• scripts/polar-webhook-verify.js - Polar webhook verification
• scripts/checkout-helper.js - Checkout session generator

Key Capabilities

Platform	Highlights
SePay	QR/bank/cards, 44+ VN banks, webhooks, 2 req/s
Polar	MoR, subscriptions, usage billing, benefits, 300 req/min
Stripe	CheckoutSessions, Billing, Connect, Payment Element
Paddle	MoR, overlay/inline checkout, Retain (churn prevention), tax
Creem.io	MoR, licensing, revenue splits, no-code checkout

Implementation

See references/implementation-workflows.md for step-by-step guides per platform.

General flow: auth → products → checkout → webhooks → events