Payment Integration

Overview

Production-proven payment processing solutions covering SePay (Vietnamese banking), Polar (global SaaS), Stripe (global infrastructure), Paddle (MoR subscriptions), and Creem.io (MoR + licensing). Includes patterns for checkout flows, subscription management, webhook handling, and multi-provider order management.

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 sharing and commissions

Platform Selection

Quick Reference

SePay

• references/sepay/overview.md -- Authentication, supported banks
• references/sepay/api.md -- API endpoints, transactions
• references/sepay/webhooks.md -- Webhook setup and verification
• references/sepay/sdk.md -- Node.js, PHP, Laravel SDK
• references/sepay/qr-codes.md -- VietQR code generation
• references/sepay/best-practices.md -- Production patterns

Polar

• references/polar/overview.md -- Authentication, MoR concepts
• references/polar/products.md -- Pricing models
• references/polar/checkouts.md -- Checkout flow
• references/polar/subscriptions.md -- Subscription lifecycle management
• references/polar/webhooks.md -- Event handling
• references/polar/benefits.md -- Automated benefit 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 docs: https://docs.stripe.com/llms.txt

Paddle

• references/paddle/overview.md -- MoR, authentication, entity IDs
• references/paddle/api.md -- Products, prices, transactions
• references/paddle/paddle-js.md -- Overlay/inline checkout
• references/paddle/subscriptions.md -- Trials, upgrades, pausing
• references/paddle/webhooks.md -- SHA256 signature verification
• references/paddle/sdk.md -- Node, Python, PHP, Go SDKs
• references/paddle/best-practices.md -- Production patterns
• External docs: https://developer.paddle.com/llms.txt

Creem.io

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

Multi-Provider

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

Core Capabilities

Implementation Workflow

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

Common flow: Authentication -> Product setup -> Checkout -> Webhooks -> Event handling