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fastapi

Idempotency Keys: How to Make Retries Safe in Distributed Systems

Last Updated on: October 14, 2026 by Anup Das
Idempotency keys: a POST and its retry with the same key produce one 201 response

A timeout can’t tell you whether the card was charged, so an idempotency key lets the retry get the original result back instead of charging twice.

Anup Das

I’m an Applied AI Systems Architect sharing practical deep dives on System Design, Backend Architecture, GenAI Infrastructure, and scalable Python applications.

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