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

# Authentication

Authenticate your account by including your **secret API key** in every request.\
You can create and manage API keys from the <a href="https://app.pdfshift.io" target="_blank">Dashboard</a>.

Send your key using the following HTTP header:

`X-API-Key: sk_xxxxxx.....`

<Warning>
  If the `X-API-Key` header is **absent**, **empty**, or **malformed**, the API will treat the request as coming from a **free account**.

  Free accounts are subject to **more restricted limits and capabilities** than authenticated requests.
</Warning>

## Free or unauthenticated account limits

Free (or unauthenticated) accounts can access the same PDFShift endpoint to convert a document, but with very restricted usage.

Specifically:

1. Generated documents include a watermark, even if `sandbox` is set to `false`.
2. Documents larger than **2 MB** cannot be converted.
3. Requests have a shorter timeout of **30 seconds**.
4. You can only do **up to 10 conversions per day**.
5. Parallel requests are not allowed.

If you believe you are sending your API key using the `X-API-Key` header but are still seeing these restrictions, it likely means the request is malformed (for example, the header name is incorrect or the key is not properly formatted).

Don’t hesitate to reach out to us in that case — we’ll help you sort it out.