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

# Headers

### Authorization

This is a required header in the form of `Bearer <token>`. It is used to authenticate all requests against the API.

### x-user-id

Some Asset API operations accept an optional `x-user-id` request header. When you send it, we associate the call with
that identifier so we can **track user actions on specific resources** .

The header is **optional**. Endpoints behave the same whether or not you include it.

Use a stable value your platform already uses to represent a person or service account (for example, the user's email
address). In the **API Reference** tab, each operation documents this header when it is supported.

<Note>
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