> ## Documentation Index
> Fetch the complete documentation index at: https://supertone-b89202c8.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> All Supertone API requests authenticate with an API key sent in the `x-sup-api-key` header.

The Supertone API uses an API-key authentication scheme with a custom header.

## Header

```http theme={"dark"}
x-sup-api-key: <YOUR_API_KEY>
```

Include this header on every request. Missing or invalid keys return `401 Unauthorized`; keys without permission for the resource return `403 Forbidden`.

## Issue a key

Sign in at the [developer console](https://console.supertoneapi.com) and create a new key. You can have up to **3 active keys per account**; revoke and reissue from the console at any time.

## Example

```bash theme={"dark"}
curl https://supertoneapi.com/v1/voices \
  -H "x-sup-api-key: $SUPERTONE_API_KEY"
```

## Authentication errors

| Status | Cause |
| - | - |
| `401 Unauthorized` | Missing, malformed, or revoked API key. |
| `403 Forbidden` | Valid key, but no permission for the resource (e.g. calling a custom voice owned by a different account). |

For the full error catalog and recommended responses, see [Error handling](/en/docs/production/error-handling).

## See also

> **[Docs: Authentication](/en/docs/authentication)**
>
> Setup walkthrough, env-var conventions, and security checklist.

> **[Quickstart](/en/docs/quickstart)**
>
> Set your key and make your first call in five minutes.


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