> For the complete documentation index, see [llms.txt](https://developers.firstbase.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.firstbase.com/getting-started/authentication.md).

# Authentication

To access the Firstbase API, you must authenticate each request by including a valid API key. API key-based authentication ensures that only authorized users can interact with the API. Without this key, requests will be denied.

Every API request requires the Authorization header with your API key. When making API requests, include the API key in the request header using the following format:

```bash
Authorization: ApiKey YOUR_API_KEY_HERE
```

Replace `YOUR_API_KEY` with the key you generated from your Firstbase account. This key provides access to your account’s data, so it’s essential to keep it secure.

### Handling Authentication Errors

If authentication fails, the API will return a `401 Unauthorized` error. This occurs if the Authorization header is missing, the API key is incorrect, or the key has been revoked. In order to resolve this, follow these steps:

* Double-check that the API key is correct and properly formatted.
* Ensure the Authorization header is included in every request.
* Verify that the key hasn’t been deleted or expired.


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