---
id: idempotency
title: "Idempotency"
---

:::tip Retry safely with an idempotency key
A response you never receive, because of a network problem for example, leaves you unsure whether
the request went through. Retrying it blind risks doing the same thing twice.

Generate a v4 UUID and send it as the `Walley-Idempotency` header on every unique operation:

`Walley-Idempotency: 03304b06-cb33-4f78-bcea-86cb4b202ba0`

Retry with the same key and Walley applies the operation only once.
:::