---
title: Idempotency
description: Idempotency-Key header for safe retries within 24 hours.
locale: en
---

# Idempotency

Send the header:

```
Idempotency-Key: <unique string>
```

If the same key is reused on the same path within **24 hours**, the API returns the cached response instead of creating another send.

Use IDs from your system (order UUID, notification id, etc.).