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

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

Implementation

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

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