# Idempotency Key

A unique value that stops a retried POST from happening twice.

## What is **Idempotency Key**?

An **idempotency key** is a unique value the client sends with a POST so that retrying the same request (after a timeout) doesn't create a second order or charge.

```text
POST /payments
Idempotency-Key: 7c1e9a2b-order-981
```

Level: Freelancer · [More REST API terms at this level](https://www.ask-codey.com/glossary/subjects/rest-api/freelancer)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/idempotency-key