> ## Documentation Index > Fetch the complete documentation index at: https://docs.engine.usesophic.com/llms.txt > Use this file to discover all available pages before exploring further. # Idempotency > Prevent duplicate operations by using idempotency keys. Support for idempotency is currently under development The API supports idempotency to safely retry requests without accidentally performing the same operation multiple times. This is especially useful when network errors occur; you can retry the request without worrying about duplicate charges, double creations, or repeated updates. To use idempotency, include an `Idempotency-Key` header with your request. The API stores the response for the first request with a given key and returns the same result for any subsequent requests using that key **within 24 hours** (after which the key expires and can be re-used). ```bash theme={"theme":"catppuccin-mocha"} curl -X POST https://api.engine.usesophic.com/orders \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Idempotency-Key: a1b2c3d4-e5f6-7890-abcd-ef1234567890" ``` The format of the idempotency key is up to you; we recommend using a UUID or random string with sufficient entropy to avoid collisions. Keys can be up to 255 characters long; we will reject any request with an `Idempotency-Key` header that is longer than 255 characters. The API saves both successful and failed responses, **including server errors**. If you retry a request with the same idempotency key but different parameters (query, body and/or headers), the API will return an error to prevent accidental misuse. Keys are only stored after validation passes and execution begins, so validation failures can be safely retried.