TL;DR
- idempotency key api retry 2026
- For backend engineers building order, payment, and webhook APIs.
Who this is for
- For backend engineers building order, payment, and webhook APIs.
Keyword (SEO)
idempotency key api retry 2026
The problem
- Clients retry the same POST after timeouts-without a key you can double charge or duplicate orders.
- Mobile networks and proxies increase duplicate risk.
The pattern
- Send Idempotency-Key (UUID) per business operation.
- Store key hash + response snapshot with TTL-replays return the same status/body.
- Align TTL with PSP rules and your own risk window.
Integrations
- Many PSPs support idempotency-map consistently.
- Verify webhook signatures before mutating state.
Common mistakes
- Clients retry the same POST after timeouts-without a key you can double charge or duplicate orders.
- Mobile networks and proxies increase duplicate risk.
FAQ
Should GET be idempotent?
GET should be safe to repeat; keys matter most for POST/PUT with side effects.
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About the author
We build fast websites, web/mobile apps, AI chatbots and hosting setups — with a focus on SEO and conversion.
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