Fraud Detection, Risk Management, and the ML Engine Behind PayPal's Trust Layer

PayPal's fraud detection and risk management systems are among the most sophisticated in fintech, analyzing 500+ data points per transaction in real time across a network processing $1.79 trillion annually. From the Quokka shadow platform to AI-powered scam alerts for P2P payments, PayPal's ML infrastructure is a core differentiator. This module dives deep into the technical and product aspects of PayPal's trust and safety systems -- a topic that frequently appears in system design interviews and demonstrates genuine understanding of what makes payments hard.