System design interview question
Design a Distributed Financial Transaction Settlement System like Stripe's Payment Clearing
Design a fault-tolerant, globally-distributed settlement system that processes and clears financial transactions across multiple payment networks (card networks, ACH, wires) with 100M+ merchants and 1B+ daily transactions. The system must guarantee exactly-once settlement semantics, provide sub-second transaction status updates to merchants and acquirers, maintain strict audit trails for regulatory compliance (PCI-DSS, SOX), handle transaction reversals/chargebacks, and support idempotent retry logic across regional data centers with eventual consistency constraints. Key constraints: latency <5s from transaction submission to clearing queue, 99.99% uptime SLA, cross-border currency conversion support, and ability to detect and prevent fraud patterns in real-time while maintaining transactional integrity during network partitions.
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