API Explorer

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.

Authentication

The API Explorer supports all authentication schemes configured in your OpenAPI spec or in generators.yml, including 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.

Multiple environments

When multiple server URLs are configured in OpenAPI or the Fern Definition, users can switch between environments (e.g., production and sandbox) from a dropdown in the API Explorer. The selected environment persists as they navigate between pages.

Users can also double-click the server URL to manually edit it, allowing for quick testing against custom environments or endpoints.

Here’s an example of the Flagright docs site with multiple server names configured.

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openapi: 3.0.0
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servers:
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  - url: https://sandbox.api.flagright.com
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    x-fern-server-name: Sandbox API server (eu-1)
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  - url: https://sandbox-asia-1.api.flagright.com
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    x-fern-server-name: Sandbox API server (asia-1)

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.

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 extension. This is commonly used to disable the Explorer for destructive operations, payment processing, or admin-only endpoints.