# API Idempotency

[View original](https://ittybit.com/api/idempotency)

### Idempotency-Key Header

You can use the `Idempotency-Key` header to deduplicate `POST` requests.

If you include this header in your request, we will ensure that the request is only processed once, even if it is made multiple times.

<Tabs items={["request.js", "request.sh"]}>
  <Tab value="request.js">
    ```js
    const response = await fetch(`https://api.ittybit.com/files`, {
      method: "POST",
      headers: {
        "Authorization": "Bearer ITTYBIT_API_KEY",
        "Idempotency-Key": "my-unique-idempotency-key",
      },
      body: JSON.stringify({
        url: "https://ittyb.it/sample.mp4",
      }),
    });
    ```
  </Tab>

  <Tab value="request.sh">
    ```shell
    curl -X POST https://api.ittybit.com/files \
    -H "Authorization: Bearer ITTYBIT_API_KEY" \
    -H "Idempotency-Key: my-unique-idempotency-key" \
    -d '{"url": "https://ittyb.it/sample.mp4"}'
    ```
  </Tab>
</Tabs>

This is useful for requests that may be retried by your system, for example if your system crashes before it can process the response from the API.

***

## Valid Keys

The `Idempotency-Key` header must be a unique string between 16 and 32 characters in length.

A good option is to [generate a hash](https://en.wikipedia.org/wiki/Hash_function) from the values you are sending in the request.

***

## Expiry

Idempotency keys are valid for \~24 hours from first creation. After this time, the key will expire and the request will no longer be deduplicated.

***

## Errors

Sending different request bodies with the same `Idempotency-Key` will result in an error.