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

# Authentication

> Authenticate production and test API requests.

CarHub API keys authenticate your server, worker or trusted backend. Use the key that matches the environment you are calling.

## Inference API keys

Use an organisation API key for `/v1/*` and `/mcp`.

```http theme={null}
Authorization: Bearer chk_live_… or chk_test_…
```

| Key prefix  | Inference              | Credits      | `livemode` |
| ----------- | ---------------------- | ------------ | ---------- |
| `chk_live_` | Production models      | Live balance | `true`     |
| `chk_test_` | Deterministic fixtures | Test balance | `false`    |

The secret is shown once when you create or rotate a key. Store it in a secret manager. CarHub stores only a hash and later displays the key prefix.

Keys can be restricted to endpoint families. A call outside the allowed scope returns `403 scope_not_granted`.

Use a `chk_test_` key while you build and verify error handling. It exercises the same authentication, rate limits, idempotency, job lifecycle and webhook delivery as a live key. Only model execution is replaced by a deterministic fixture. See [test mode](/guides/test-mode).

<Warning>The inference API intentionally does not return CORS headers. Call it from your server, worker or trusted backend—not directly from browser code.</Warning>