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idempotency-design

Design idempotent APIs using idempotency keys, deduplication, and retry-safe implementations.

1|Updated Mar 21, 2026
Search Tags:#redis#api design#retry logic#deduplication#payments#idempotency#distributed locks
One-click install
npx skills add https://github.com/kalilurrahman/kr-claudiator-skills-original-prompts --skill idempotency-design-kalilurrahman
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: idempotency-design
Source: https://github.com/kalilurrahman/kr-claudiator-skills-original-prompts/tree/main/01-software-dev/idempotency-design
Command: npx skills add https://github.com/kalilurrahman/kr-claudiator-skills-original-prompts --skill idempotency-design-kalilurrahman

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Non-idempotent operations like payments and order creation cause duplicate charges, double bookings, and data corruption when clients retry after network timeouts or failures. ## Core Features & Use Cases - Idempotency Keys: Client-generated UUIDs with server-side deduplication using Redis caching or database unique constraints. - Distributed Locking: Redis-based locks prevent race conditions when concurrent requests share the same idempotency key. - Retry Logic: Exponential backoff strategies with safe retry policies for POST, PUT, and DELETE requests. - Use Case: A payment API receives a POST request that times out; the client retries with the same Idempotency-Key header and receives the cached original response instead of charging the customer twice. ## Quick Start Design an idempotent payment endpoint with idempotency keys, Redis deduplication, and retry logic for my Flask API.

Frequently Asked Questions about idempotency-design

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I make a POST API endpoint idempotent?▼

Require clients to send a unique Idempotency-Key header (typically a UUID) with each request. The server stores processed keys in Redis or a database and returns the cached response when a duplicate key arrives instead of re-executing the operation.

Redis vs database unique constraint for idempotency deduplication?▼

Redis offers fast lookups with automatic TTL expiration, ideal for high-throughput APIs. Database unique constraints provide stronger durability guarantees. Using both together gives defense in depth for critical operations like payments.

How long should idempotency keys be cached?▼

Cache responses for at least 24 hours to cover typical retry windows after failures. The examples use a 24-hour TTL for API responses and 7 days for email send markers, with daily cleanup jobs for database-stored keys.

How do I prevent race conditions with concurrent idempotent requests?▼

Use a distributed lock via Redis SET NX with an expiration timeout around the check-and-process logic. Requests that fail to acquire the lock receive a 409 Conflict response indicating the operation is already processing.

Does Stripe support idempotency keys for payments?▼

Yes, Stripe accepts an idempotency_key parameter on charge creation and handles deduplication server-side. Reusing the same key with different parameters raises an IdempotencyError, while identical retries return the original charge.

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