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

# Authentication

> Authenticate every request with the X-Api-Key header.

All v3 requests authenticate with a single header.

| Header      | Type              | Description                                                                                                |
| ----------- | ----------------- | ---------------------------------------------------------------------------------------------------------- |
| `X-Api-Key` | string · required | Your 60-character hex API key. Generate it in the [dashboard](https://cryptorank.io/public-api/dashboard). |

```bash theme={null}
curl https://api.cryptorank.io/v3/currencies/map \
  -H "X-Api-Key: YOUR_API_KEY"
```

## Key facts

* Keys are **shared with v2** — an existing v2 key works on v3.
* **Credits are per user** (shared across all of your keys); **rate limit (RPM) is per key**.

## Errors

Auth failures return `401` (`API_KEY_MISSING` / `API_KEY_INVALID`) or `403 NO_ACTIVE_SUBSCRIPTION`.
See [Errors](/errors) for the full list.