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# Generate REST API Reference

> Use Fern Docs to generate REST API Reference documentation from an OpenAPI spec.

Fern generates REST API Reference documentation from an [OpenAPI specification](/learn/api-definitions/openapi/overview). Once the API definition is set up, adding it to the docs takes just one line of configuration.

Fern also supports [gRPC](/learn/docs/api-references/generate-grpc-ref), [WebSocket](/learn/docs/api-references/generate-websocket-ref), [OpenRPC](/learn/docs/api-references/generate-openrpc-ref), and [Webhook](/learn/docs/api-references/generate-webhook-ref) references.

## Configuration

#### Set up your project structure

Add your specification file to your `/fern` directory and create a `generators.yml` that references it in the `api.specs` section:

**`generators.yml`**

```yaml generators.yml
api:
  specs:
    - openapi: "./openapi.yml"
```

#### Add the API Reference to your navigation

Add `- api: API Reference` to your navigation in `docs.yml`:

**`docs.yml`**

```yml docs.yml
navigation:
  - api: API Reference
```

Fern will automatically populate your endpoints, types, and code snippets from your API definition. Request and response examples are [generated using AI](/learn/docs/ai-features/ai-examples) to show realistic data instead of placeholder values.

#### Customize the layout

For a full list of configuration options and layout customizations, see [Customize API Reference layout](/learn/docs/api-references/customize-api-reference-layout).

### Include more than one API Reference

To include multiple, distinct API definitions in your documentation, use the `api-name` property. The `api-name` corresponds to the folder name containing your API definition. For example:

#### Flat layout

For a simple setup without tabs, you can include multiple API References directly in your navigation:

**`docs.yml`**

```yaml title="docs.yml"
navigation:
  - api: Plant Store
    api-name: plant-api   # Matches folder name containing your API definition
  - api: Garden
    api-name: garden-api  # Matches folder name containing your API definition
```

#### Tabbed layout

When using tabs, each API Reference must be placed within a tab's `layout`:

**`docs.yml`**

```yaml title="docs.yml" {12, 17}
tabs:
  plant-api:
    display-name: Plant Store API
    icon: leaf
  garden-api:
    display-name: Garden API
    icon: tree
navigation:
  - tab: plant-api  # References the tab defined above
    layout:
      - api: Plant Store API
        api-name: plant-api  # Matches folder name containing your API definition
        skip-slug: true
  - tab: garden-api  # References the tab defined above
    layout:
      - api: Garden API
        api-name: garden-api  # Matches folder name containing your API definition
        skip-slug: true
```

> Use Fern Docs to generate REST API Reference documentation from an OpenAPI spec.