# API Explorer

> Reduce "time to 200" by allowing users to make real calls to your API from right within the API Reference.

Fern's API Explorer allows users to make authenticated requests to your API without ever leaving your documentation.

## Autopopulate with examples

Fern will automatically populate the fields of the endpoint with the values set in your API specification.

<div>
  <iframe src="https://www.loom.com/embed/a48d921459b54dde9652c3fcc85ebc54?sid=2c0b4f4d-7e24-4fc5-a617-8d933195bfec?hide_owner=true&hide_share=true&hide_title=true&hideEmbedTopBar=true" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen />
</div>

## Authentication

The API Explorer supports all authentication schemes configured in your OpenAPI spec, including [multiple authentication schemes](/learn/api-definitions/openapi/authentication#multiple-authentication-schemes). When multiple schemes are available, the API Explorer automatically displays them in a dropdown menu, allowing users to select and configure their preferred authentication method before sending requests.

Once a user sets their authentication credentials, their credentials persist throughout their entire exploration session.

<div>
  <iframe src="https://www.loom.com/embed/7de9948ae878448094b5e92da5effd41?sid=702889b7-aa3d-4669-994e-83c196d7bc3e?hide_owner=true&hide_share=true&hide_title=true&hideEmbedTopBar=true" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen />
</div>

<Info>
  Authentication credentials are only stored client-side using cookies. No sensitive user information is collected or stored.
</Info>

## Multiple environments

Allow users to test their calls in a sandbox environment or select the environment relevant to them. Users can switch between multiple environments. Once they've selected their environment, it persists throughout their entire exploration.

<div>
  <iframe src="https://www.loom.com/embed/cb642161678e41cabcb677b900006f40?sid=5e45243c-3ba1-45cf-860b-72eee1970fc5?hide_owner=true&hide_share=true&hide_title=true&hideEmbedTopBar=true" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen />
</div>

## WebSocket Playground

For APIs that support WebSocket connections, the API Explorer includes a **WebSocket**-specific Playground. The WebSocket Playground also allows users to establish a connection with the API, and send/receive messages in real-time.

<div>
  <iframe src="https://www.loom.com/embed/be4da30404794e9983c4fe639f78d4c8?sid=73b7aeda-98fa-4531-87ed-1e5909500fe2?hide_owner=true&hide_share=true&hide_title=true&hideEmbedTopBar=true" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen />
</div>

## Control API Explorer availability

For OpenAPI specs, the API Explorer is enabled by default for all endpoints. You can disable it globally or per endpoint using the [`x-fern-explorer`](/learn/api-definitions/openapi/extensions/api-explorer-control) extension. This is commonly used to disable the Explorer for destructive operations, payment processing, or admin-only endpoints.