NestJSRedisREST APIsSystem DesignJun 2025 · 6 min read
Idempotent API Requests & Duplicate Handling in Production
How to protect critical payment and order endpoints from network retries and duplicate user submissions using Redis locks.
Network blips and rapid user double-clicks can trigger duplicate operations. Implementing Idempotency-Key headers backed by Redis ensures each unique request is executed exactly once.
1. Implementing Idempotency Key Middleware
Store request keys in Redis with SET key NX EX 60. If the key exists, return the cached result or a 409 Conflict while in progress.