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

# Authentication

> How to authenticate with the ShuttleAI API.

## API Key

All requests to the ShuttleAI API must include a valid API key in the `Authorization` header.

### Header format

```
Authorization: Bearer shuttle-xxx
```

### Getting a key

1. Sign up at [shuttleai.com](https://shuttleai.com/auth/register)
2. Go to [API Keys](https://shuttleai.com/keys)
3. Copy your master key or create a sub-key

### Example request

```bash theme={null}
curl https://api.shuttleai.com/v1/models \
  -H "Authorization: Bearer shuttle-xxx"
```

## Key format

ShuttleAI API keys always start with the `shuttle-` prefix. If your key doesn't start with `shuttle-`, it's not a valid ShuttleAI key.

## Error responses

| Status  | Description                              |
| ------- | ---------------------------------------- |
| **401** | Missing or invalid API key               |
| **402** | No active plan on the account            |
| **403** | Plan doesn't include the requested model |
| **423** | Account suspended                        |

For full error details, see [Error Codes](/guides/error-codes).