Design a scalable banking system

Q: Design a scalable banking system

This is a System Design interview question from Meta for Software Engineer roles. View the full question and solution on PracHub.

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Question

System Design: Core Banking Platform

Problem

Design a banking system that supports:

Account creation
Balance inquiry
Deposit and withdrawal
Atomic transfers between accounts, including cross-currency

Specify:

External APIs (with idempotency)
Data model (double-entry ledger)
Transaction flows guaranteeing ACID, overdraft prevention, and concurrency control
Durability, auditability, reconciliation, and cross-service consistency
Scaling strategy (sharding/partitioning)
Failure handling (sagas vs. distributed transactions)
Security (authentication, authorization, encryption, PCI considerations)
Rate limiting and monitoring

Assume you are designing for a high-traffic consumer banking workload with mobile/web clients and internal services. You may introduce minimal context (e.g., a base reporting currency) where needed.

Design a scalable banking system

System Design: Core Banking Platform

Problem

Solution (Locked)

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