Practice · High Level Design · Money and Strong Consistency
Design a Mobile Wallet
IntermediateDouble-entry ledgerIdempotencyReconciliationSagas⏱ 3-4 h
A bKash-style wallet where money must never be lost or doubled: double-entry ledgers, idempotent transfers, handling failures midway, and daily reconciliation.
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- 01Problem introduction
- 02Problem statement
- 03Requirements
- 04Capacity estimation
- 05API design
- 06Database design
- 07Architecture
- 08Request lifecycle
- 09Component deep dive
- 10Scaling, 100 to 10M users
- 11Failure scenarios
- 12Reliability and observability
- 13Security
- 14Trade-offs
- 15Final architecture
- 16Interview discussion
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