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

# Authentication

Use a Nango API key as a Bearer token in the `Authorization` header.

```
Authorization: Bearer <NANGO-API-KEY>
```

Nango has two API key types. They are not interchangeable:

* **[Environment API keys](https://nango.dev/docs/reference/backend/http-api/api-keys.md#environment-api-keys)** — access a single environment. Manage them under **Environment Settings > API Keys**. Each key has [scopes](https://nango.dev/docs/reference/backend/http-api/api-keys.md#scopes) that control which environment endpoints it can access. A key without the required scope receives a `403 Forbidden` response.
* **[Account API keys](https://nango.dev/docs/reference/backend/http-api/api-keys.md#account-api-keys)** — access [account-level APIs](https://nango.dev/docs/reference/backend/http-api/api-keys.md#account-level-apis) only. Requests to environment-level APIs with an Account API key return a `403 Forbidden` response. Manage them from [Account API keys](https://app.nango.dev/api-keys) in the dashboard.


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