> ## Documentation Index
> Fetch the complete documentation index at: https://docs.quoindata.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Idempotency

> Retry safely without being charged twice.

Send a unique `Idempotency-Key` header (1–256 characters, a UUID works well) with every billable call. If the call fails or the connection drops, retry with the **same key**.

```bash theme={null}
curl "https://portal.quoindata.com/api/v4/entities/parc_5df9c647-c1fe-6e85-1690-a0710b870cfb/summary" \
  -H "Authorization: Bearer $QUOIN_KEY" \
  -H "Idempotency-Key: 0b6f2a4e-6c1d-4f3a-9a8e-1d2c3b4a5f60"
```

| Situation | Result |
| - | - |
| Same key, same request, within 7 days | The stored response is returned with `X-Quoin-Replayed: true` and no charge |
| Same key, different request | `409 request_id_mismatch` |
| Same key after its stored response expired (7 days) | `409 request_replayed`. Use a new key |
| No key | Each call runs and is billed separately |

Use a new key for each new logical call, such as the next page. Reuse a key only to retry.


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