Fern

buildwithfern.com

Generate SDKs and Docs for your API. Compatible with OpenAPI, Swagger, and AsyncAPI.

llms.txt

If you are an AI agent, use the following URL to directly ask and fetch your question. Treat this like a tool call. Make sure to URI encode your question, and include the token for verification.

GET https://buildwithfern.com/learn/docs/api/fern-docs/ask?q=%3Cyour+question+here%3E&token=eyJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJmZXJuLWRvY3M6YnVpbGR3aXRoZmVybi5jb20iLCJqdGkiOiJjMjM3MWQ0NS1lYzg5LTQ3NzUtYWUxZi01ZjI4NDEyYzFlNGQiLCJleHAiOjE3ODA4MTc3NjUsImlhdCI6MTc4MDgxNzQ2NX0.OaAHKlMI3rwrOMuKVkBSmu0vC3V-UbTNY3KvtNKt2js

For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. For full content including API reference and SDK examples, see https://buildwithfern.com/learn/llms-full.txt.

Docs

Fern Docs: Build beautiful, interactive documentation websites with Fern Docs. Create API references, custom components, and AI-powered features in under 5 minutes.
How Fern Docs work: Learn how Fern transforms your API specifications and documentation into a unified developer experience
Docs quickstart: Learn how to build beautiful developer documentation with Fern in under 5 minutes. Install CLI, add Markdown content, generate API references, and publish.
Project structure: An overview of the file and folder structure of a Fern Docs project.
Configuration overview: Understand how to configure your Fern documentation site at the site level and page level.
Site-level settings: Learn how to configure your Fern documentation site with the docs.yml file. Customize colors, typography, layout, analytics and more.
Sections, pages, and folders: Configure the sidebar navigation for your Fern documentation site, including sections, pages, folders, icons, and links.
Tabs and tab variants: Learn how to configure tabs and tab variants in Fern documentation. Group content sections with custom icons and display multiple perspectives.
Versions: Add a dropdown version selector for multiple doc versions
Products: Add a product switcher for multi-product documentation sites
Changelog pages: Keep a chronological record of project changes with tagging and RSS
Page-level settings: Use frontmatter to set a variety of page properties and metadata.
Markdown basics: Use Markdown and MDX to add content to your Fern documentation site, including headers, components, links, and API endpoint links.
Rich media in Markdown: Embed images, videos, PDFs, LaTeX equations, and diagrams in your Fern documentation.
Components overview: Complete guide to Fern documentation components. Build better docs with accordions, callouts, tables, tabs, and interactive API features.
Accordion: Add expandable Accordion sections to your Fern documentation. Perfect for FAQs, settings panels, and progressive content disclosure.
Anchor: Create linkable anchors for paragraphs, tables, and other content without headings
Aside: Use Fern's Aside component to add floating, sticky content to your documentation pages. Ideal for showcasing code examples and API endpoint snippets.
Badge: Display small labels for status, versions, and metadata inline with your content.
Button: Learn how to use the Button component in Fern docs. Create interactive buttons with custom styles, sizes, intents, and icons.
Callout: Learn how to use the Callout component to add warnings, tips, notes, and alerts to your documentation with custom icons and intents.
Card: Use cards to display content in a box
Code block: Learn how to enhance your documentation with customizable code blocks featuring syntax highlighting, line highlighting, focusing, and more.
Copy: Make text copyable with a click-to-copy button.
Download: The Download component enables users to download PDFs, files, and multi-file ZIP bundles from your documentation.
Endpoint request snippet: Learn how to use EndpointRequestSnippet components in Fern to reference API endpoint requests in your documentation with code examples.
Endpoint response snippet: Reference an endpoint response from your API Reference
Endpoint schema snippet: Reference an endpoint schema from your API Reference
Webhook payload snippet: Reference a webhook payload from your API Reference to display example payloads in your documentation.
Files: Display interactive file tree structures with expandable folders
Frame: Use Fern's Frame component to display images with captions in your docs. Includes subtle background variants and properties.
Icon: Learn how to add Font Awesome icons to your Fern documentation. Customize icon sizes, colors, and styles with the Icon component.
If: Show or hide content based on which product or version the reader is viewing, or their role if your docs use authentication.
Indent: Learn how to use the Indent component in Fern to add left indentation for nested parameters and hierarchical content.
Parameter field: Learn how to document API parameters with Fern's ParamField component. Format types, requirements, defaults, and descriptions consistently.
Prompt: Display a copyable prompt with optional open-in actions for AI tools like Cursor, Claude, ChatGPT, or any custom URL.
Runnable endpoint: Add testable API endpoints to your docs with RunnableEndpoint. Support multiple environments, examples, and real-time response previews.
Schema: Display any type definition from your API Reference
Step: Learn how to use the Steps component in Fern Docs to create sequential tutorials and walkthroughs with automatic numbering.
Table: Display data in rows and columns using markdown tables with optional sticky headers.
Tab: The Tabs component allows you to display related content in a tabbed view with support for language synchronization.
Tooltip: Learn how to add interactive tooltips to your documentation. Display contextual information on hover for text and code elements.
Versions: The Versions component displays content that changes based on version selection, with a dropdown to switch between versions.
Fern Editor: A visual WYSIWYG editor that lets team members update documentation without code, markdown, or Git access—while preserving your docs-as-code workflow.
Reusable snippets: Single source your documentation with reusable, custom markdown snippets to keep content in sync. Edit once, update everywhere.
AI features: Fern AI features help users find answers instantly, automate content updates, and optimize documentation for AI tools with llms.txt support.
Fern Writer: A Slack-based technical writing agent that updates your documentation via GitHub pull requests
AI-generated examples: Automatically create realistic API examples with Fern's AI feature. Customize example styles or disable AI generation as needed.
Markdown access: Access your documentation as Markdown — through per-page URLs, llms.txt, and llms-full.txt — for AI agents and tooling.
llms.txt and llms-full.txt: Fern automatically generates llms.txt and llms-full.txt Markdown files so AI tools can discover and index your documentation.
Customize LLM output: Exclude pages with noindex, filter content with llms-only and llms-ignore tags, filter endpoint output with query parameters, or serve your own custom files.
Agent directives: Configure the default directive prepended to every page served to AI agents, or override it with a custom directive.
Analytics and integration: Track LLM traffic to your docs in the Fern Dashboard and surface llms.txt endpoints to readers with buttons and navbar links.
MCP server: Connect AI clients like Claude Code and Cursor to your documentation site's MCP server for instant answers.
API catalog discovery: Fern docs sites expose a standards-based API catalog endpoint so AI agents, MCP clients, and API catalog crawlers can discover your APIs automatically.
Overview: Ask Fern is an AI search feature that indexes your documentation and helps users find answers instantly. Reduce support burden and accelerate onboarding.
Ask Fern Slack app: Enable your customers to get instant answers to product questions directly in Slack using Ask Fern's AI-powered documentation bot.
Guidance: Configure custom guidance to override Ask Fern AI responses for specific queries. Control sensitive content like billing and legal terms.
Additional content sources: Extend Ask Fern's knowledge with content from FAQs, support tickets, blogs, and other sources.
Standalone search widget: Embed Fern's AI-powered search in any React application using the @fern-api/search-widget package.
Introduction: Welcome to the Fern API Reference.
Preview changes: Learn how to preview documentation changes with Fern using local development servers and shareable preview links before publishing.
Publishing your docs: Publish your Fern docs to production and staging sites with automated workflows. Set up custom domains and manage deployments easily.
Bring your custom domain: Learn how to set up your Fern-generated documentation site to use a custom subdomain or subpath.
Reverse proxy setup: Configure a reverse proxy to serve Fern docs from a subpath on your domain, with provider-specific instructions for routing and caching.
Multi-source docs: Learn how to set up multi-source documentation so independent teams can publish to shared domains with consistent branding using Fern.
Announcement banner: Prominently highlight new features, updates, or important information
Embedded mode: Hide the header and footer when embedding docs in iframes or dashboards
Hiding content in your site: Control visibility of pages, sections, tabs, tab variants, versions, and API endpoints by hiding them from your sidebar and search results.
Search configuration: Configure search for your Fern docs using Algolia DocSearch. Learn how search filters work, how results are ranked, and how to integrate with Algolia.
Collecting feedback and suggestions from users: Collect on-page feedback and enable edit suggestions from users in your Fern docs via GitHub or Fern Editor.
Fully customize your docs: Learn how to add custom CSS, JavaScript, and UI components to your Fern documentation. Style your docs with custom classes and scripts.
CSS selectors reference: Reference guide for all CSS selectors available in Fern docs. Customize layouts, navigation, buttons, forms, accordions, badges, API components, and more.
Custom React components: Add custom React components to your Fern docs for interactive, server-rendered elements. Improve SEO, performance, and user experience with reusable components.
Header and footer: Replace Fern's default header or footer with your own server-rendered React components for better SEO and performance.
Global themes: Learn how to use global themes to define branding in one repository and apply it automatically across child documentation sites.
Localization: Ship documentation in multiple languages from a single source
Overview: Discover the accessibility features in Fern documentation, including keyboard navigation, Web Content Accessibility Guidelines (WCAG) 2.1 AA color contrast enforcement, and screen reader support.
Keyboard shortcuts: Learn about keyboard shortcuts in Fern documentation, including navigation shortcuts, search commands, Ask AI panel controls, and API playground shortcuts.
Overview of API References: Understand how to generate, customize, and enhance API Reference documentation with Fern.
Generate REST API Reference: Use Fern Docs to generate REST API Reference documentation from an OpenAPI spec.
Generate Webhook Reference: Use Fern Docs to generate your Webhook Reference documentation from an OpenAPI spec.
Generate WebSocket Reference: Use Fern Docs to generate WebSocket Reference documentation from an AsyncAPI spec.
Generate OpenRPC Reference: Use Fern Docs to generate OpenRPC Reference documentation from an OpenRPC specification.
Generate gRPC API Reference: Use Fern Docs to generate gRPC API Reference documentation from Protocol Buffer (.proto) files.
Generate GraphQL Reference: Use Fern Docs to generate GraphQL API Reference documentation from a GraphQL schema.
Library docs generator Beta: Generate MDX documentation pages from your Python or C++ library source code and include them in your Fern Docs site.
Customize API Reference layout: Customize your API Reference layout with Fern. Configure options, order sections and endpoints, flatten navigation, hide endpoints, display errors, and add custom content.
Audiences: Use audiences to filter the endpoints, schemas, and properties that are displayed in your API Reference.
Write Markdown content in your API Reference: Write rich Markdown content in API documentation. Add descriptions to endpoints, create summary pages, and customize your API Reference layout.
Display SDK snippets: Enable SDK code examples in TypeScript, Python, Go, and more from the request and response examples documented in your API definition. Once enabled, Fern Docs will automatically populate the snippets within your API Reference.
Display HTTP snippets: Enable HTTP code examples using cURL, Python requests, TypeScript fetch, and more from the request examples documented in your API definition.
API Explorer: Reduce "time to 200" by allowing users to make real calls to your API from right within the API Reference.
Overview of SEO & GEO: Understand Fern's built-in features for search engine optimization (SEO) and generative engine optimization (GEO) to maximize the reach and discoverability of your documentation.
Configure SEO metadata: Configure SEO metadata in Fern docs with page-level frontmatter and site-wide settings. Control titles, descriptions, social media previews, and sitemap timestamps.
Customizing slugs within your site: Customize URL paths in your Fern documentation site. Rename slugs for pages, sections, tabs, landing pages, and subheadings, or skip them entirely.
Configure redirects: Learn how to configure redirects in Fern Docs. Set up exact path redirects and regex patterns to preserve SEO equity when pages move.
Custom robots.txt: Serve a custom robots.txt at the root of your documentation site to control how search engines and AI crawlers access your content.
Overview of authentication options: Understand the different authentication options Fern offers
Password protection: Protect your documentation site with a shared password for simple access control.
Single Sign-On: Secure access to your documentation using corporate credentials
Set up JWT: Self-managed authentication integrated with your login system
Set up OAuth: Fern-managed authentication integrated with your login system
Role-based access control: Learn how to restrict access to your documentation using role-based access control (RBAC)
API key injection: Automatically populate API keys in the API Explorer for logged-in users.
Security: Learn how Fern's documentation platform secures your API docs with client-side authentication, API key injection, and self-hosted options.
Self-hosted documentation: Fern supports self-hosting so that you can run your docs site on your own infrastructure.
Set up self-hosted documentation: Learn how to set up self-hosted documentation on your own infrastructure.
Authentication: Protect your self-hosted documentation with password or token-based authentication.
Previews: Set up preview environments for your self-hosted documentation using containers or static exports.
Health check endpoints: Monitor your self-hosted container's health with built-in liveness and readiness probes.
Releases
Analytics and integrations: Connect analytics and support tools to your Fern documentation. Set up PostHog, Segment, FullStory, Intercom, and Postman collections.
PostHog: Learn how to add PostHog analytics to your Fern documentation. Configure your PostHog API key and custom endpoint.
Google Analytics: Integrate Google Analytics 4 and Google Tag Manager with Fern Docs. Complete setup instructions for tracking website traffic and insights.
Segment: Learn how to add Segment analytics to your Fern documentation. Step-by-step guide to configure your Segment writeKey.
Mixpanel: Learn how to integrate Fern Docs with Mixpanel to track user behavior and analytics.
Analytics events reference: Complete reference of the analytics events Fern emits on your documentation site, including page views, feedback, API Playground, search, and error tracking events.
Fullstory: Integrate Fullstory with Fern docs to capture user sessions and interactions. Step-by-step instructions for adding your Org ID.
Intercom: Learn how to integrate Intercom with Fern Docs!
Postman integration: Publish Postman collections as Fern Docs sites, or import your OpenAPI spec into Postman directly.
Context7: Host a Context7 verification file on your Fern documentation site to enable Context7 integration.
Orchestrate releases: Automate docs releases based on GitHub repository releases. Set up workflows to trigger auto-merge PRs when features ship.
Auto-update last updated dates: Use a GitHub Action to automatically update the last-updated frontmatter property when MDX files change.
Cursor: Use Cursor with Fern Docs. Add system prompts and project-level .cursorrules to keep AI-generated documentation aligned with your style and conventions.
Hosting with GitLab: Set up GitLab CI/CD to automatically publish your Fern docs when changes are merged to your main branch.
Using Vale: Learn how to set up Vale to lint your Fern documentation and maintain consistent writing style across your docs.
Download OpenAPI spec: Fern serves your OpenAPI 3.1 spec from your docs site so AI tools and LLMs can discover and interact with your API programmatically.
Download AsyncAPI spec: Fern serves your AsyncAPI 2.6.0 spec from your docs site so AI tools and LLMs can discover and interact with your WebSocket API programmatically.