idempotency-key

What problem does it solve?

The Idempotency Key pattern ensures that multiple identical requests from a client (e.g., due to network retries, double-clicks) result in only a single execution of the operation on the server. This prevents duplicate mutations and preserves data integrity.

Core Features & Use Cases

• Header-driven deduplication: Clients must provide an Idempotency-Key header for mutating requests (POST, PUT, PATCH, DELETE).
• Middleware/Interceptor support: Implement an IdempotencyInterceptor or equivalent to capture keys and payloads.
• State management with Redis: Use a lightweight state machine (PENDING, COMPLETED, FAILED) and a TTL (e.g., 24 hours) to guard against repeated processing.
• Use cases: Guard for order creation, payments, and other operations where retries should not produce duplicates.

Quick Start

Add an IdempotencyInterceptor to your NestJS app and apply it to endpoints that mutate data using the Idempotency-Key header.