System design interview question
Design a Distributed Transaction Ledger System for a Global Payment Platform (Similar to Stripe's Settlement)
Design a distributed ledger system that processes and settles financial transactions for a global payment platform serving 200M users across 50+ countries. The system must handle 500K transactions per second at peak, maintain strict ACID guarantees with zero data loss, support real-time settlement visibility to merchants, and reconcile funds across multiple currencies and payment methods. Key constraints include sub-second latency for transaction confirmation, compliance with regional financial regulations (PCI-DSS, GDPR, local banking rules), and the ability to detect and prevent fraudulent transactions while maintaining audit trails for 7+ years. Design the core transaction processing pipeline, state management, consistency model, and how you'd handle cross-region settlement failures and eventual consistency scenarios.
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