> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt.

# Overview of API References

> Understand how to generate, customize, and enhance API Reference documentation with Fern.

Fern generates interactive API Reference documentation from an [OpenAPI specification](/learn/api-definitions/openapi/overview) or other API formats. Endpoints, type schemas, code snippets, and [AI-generated examples](/learn/docs/ai-features/ai-examples) are all populated automatically. Users can try requests directly from the docs with the [API Explorer](/learn/docs/api-references/api-explorer), and AI agents and crawlers can discover your APIs via the [API catalog](/learn/docs/ai-features/api-catalog) endpoint.

## Pick your API type

#### [REST](/learn/docs/api-references/generate-api-ref)

OpenAPI specification

#### [gRPC](/learn/docs/api-references/generate-grpc-ref)

Protocol Buffer `.proto` files

#### [WebSocket](/learn/docs/api-references/generate-websocket-ref)

AsyncAPI specification

#### [Webhook](/learn/docs/api-references/generate-webhook-ref)

OpenAPI specification

#### [OpenRPC](/learn/docs/api-references/generate-openrpc-ref)

OpenRPC specification

#### [GraphQL](/learn/docs/api-references/generate-graphql-ref)

GraphQL schema

#### [Library](/learn/docs/api-references/library-reference)

Python or C++ source code

## Customize and enhance

#### [Customize layout](/learn/docs/api-references/customize-api-reference-layout)

Reorder endpoints, filter by audience, and add Markdown content

#### [SDK snippets](/learn/docs/api-references/sdk-snippets)

Show SDK code samples alongside your endpoint documentation

#### [HTTP snippets](/learn/docs/api-references/http-snippets)

Display cURL, Python, JavaScript, and Go request examples

> Understand how to generate, customize, and enhance API Reference documentation with Fern.