Paypal

A comprehensive guide for integrating PayPal payments into applications. Covers Express Checkout with Smart Payment Buttons, IPN (Instant Payment Notification) webhook handling, recurring billing/subscriptions, and refund workflows with Python and JavaScript examples.

This skill provides comprehensive guidance for implementing billing automation systems including subscription management, dunning workflows, and payment processing. It covers Stripe and PayPal integrations with PCI-compliant patterns, webhook handling, proration calculations, and tax management for SaaS billing.