Fern

Fern

Fern is a developer experience platform that generates beautiful documentation websites, client SDKs, and a CLI from a single source of truth—your OpenAPI, GraphQL, AsyncAPI, or gRPC spec. It is built for the AI era, serving clean Markdown with auto-generated llms.txt and a built-in MCP server so AI agents and coding assistants can use your API out of the box. Key capabilities include docs-as-code publishing via GitHub, AI-powered search (Ask Fern), version and product switching, localization, and enterprise features like SSO, SCIM, and custom branding. Target users are developer relations teams, API platform engineers, and startups shipping production documentation and SDKs.

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Added on
Sep 21, 2026
OpenAPI docsSDK generationMCP serverAI search (RAG)Docs-as-codeEnterprise SSO/RBAC
Product information

Everything worth knowing about Fern

The complete picture — from everyday features to the technical detail builders and IT folks dig for.

Core features

What it actually does

OpenAPI-Driven Documentation
Your OpenAPI spec is the single source of truth. Push a change and your docs, SDKs, and MCP server regenerate automatically. No manual updates, no drift.
AI-Powered Search & Chat
Built-in 'Ask Fern' uses RAG (Retrieval Augmented Generation) with Claude 4.6 Sonnet and 4.5 Haiku to provide accurate, cited answers to user questions directly from your documentation.
Agent-Friendly by Default
Automatically serves /llms.txt and a built-in MCP server, allowing AI coding agents (Claude, Gemini, Copilot, etc.) to read, understand, and interact with your API documentation out of the box.
Multi-Format Code Generation
Generate idiomatic client SDKs in 8 languages (e.g., TypeScript, Python) and Postman collections from the same spec, ensuring your documentation, SDKs, and API testing workflows are perfectly in sync.
Docs-as-Code Workflow
Write documentation in Markdown/MDX, manage versions with Git, and use pull requests for review. Integrates with GitHub Actions, a visual web editor, and Fern Agent for Slack/Teams.
Technical capabilities
Enterprise-Grade Customization & Security
Offers custom CSS/JS, React components, design-system integration, multi-repo aggregation, SSO/SCIM/RBAC, self-hosting, and uptime SLAs for large organizations.
Analytics & Reader Insights Dashboard
Provides web analytics, search logs, user feedback, and AI chat conversation analytics to identify documentation gaps and improve developer onboarding.
Must watch videos
Fern, a Postman company, helps businesses deliver beautiful API documentation and high-quality SDKs.
10:45
Tutorial10:45
Fern, a Postman company, helps businesses deliver beautiful API documentation and high-quality SDKs.
Sandeep from Fern provided a comprehensive walkthrough covering: (1) An overview of Fern as a company (2) A live product demonstration (3) The most effective ways to engage and partner with Fern
The Death of Educational Content on YouTube
28:11
Tutorial28:11
The Death of Educational Content on YouTube
FlexiSpot Labour Day Sale is here - up to 65% off sitewide! Use code FERN50 to get an extra $50 off on all products. Check out the E7 Pro Standing Desk: 🇺🇲 https://go.flexispot.com/fern-us 🇨🇦 https://go.flexispot.com/fern-ca Full sale: https://go.flexispot.com/fern-sale (ad) Join our newsletter: https://roots.watchfern.com/ Countless AI slop channels are relentlessly copying our work. So one day we decided: enough is enough. We went undercover to investigate who’s behind them and what this flood of AI slop means for the future of educational content on YouTube. Many thanks to Dr. Akhil Bhardwaj, Prof. Dr. Andrea Löw, neo, Memeable Data and The Present Past for their valuable insights. Check out their channels: neo: https://www.youtube.com/@neoexplains Memeable Data: https://www.youtube.com/@memeabledata The Present Past: https://www.youtube.com/@ThePresentPast_ IMPERIAL: https://www.youtube.com/@IMPERIALYT/videos Sources: https://docs.google.com/document/d/14c9vJUltQuvE1tyC4zC61csEhg2GNGxymlQQzmLTt4k/edit?usp=sharing Music list: Intro: Déjà-vu - N01R Epidemic Sound: Grieg 2 Elegiac Melodies, Op. 34_ No. 2, The Last Spring - Odyssey Orchestra Cosmic Slumber - Valante Beco das Garrafas - El Equipo Del Norte SPHINX - Blue Steel Jackpot - Blue Steel Itsumo - Valante Bionic - Ethan Sloan Bad Vibrations - Stefan Ekstrom Woodwind Reviere - Daniella Ljungsberg A Truth Unwanted - Stefan Ekstrom Big Smile Boogie - Speedy The Spider Interstellar - Blue Steel Can't Handle It - Ryan James Carr Lens Distortions: Variables Prolific Prototype Awake Foundations Tom Fox: Forever Conflict Uptight Deeper Sea Attractive Forces (Variation 2) New Formalities Technically Correct Minimal Deep Synth Artlist: DELNOVA - Follow the River Ian Post - New World Tamuz Dekel - The Shoulder Tap Matooma - Dont Look Back _____ Armchair documentaries, almost weekly
The Real Truth About fern
56:51
Tutorial56:51
The Real Truth About fern
On the 18th of August, we received a letter from fern. Forty questions, seven days to answer. On the 2nd of September, they published a film about us. This is the answer. Every document in it is public. ━━━━━━━━━━━━━━━━━━━━━━━━ CHAPTERS 00:00 — The Letter 01:39 — Who Owns fern 09:32 — The One Example 14:44 — The Same Test, Run on Them 20:11 — Whose Money 24:09 — The Loan, and What Was Pledged 27:37 — Twenty-Seven Million Dollars 29:21 — The Thumbnails 35:30 — So What Is a Copy? 38:02 — So What Was the Investigation? 41:50 — The Person 44:28 — The One Fair Question 53:24 — Why Us ━━━━━━━━━━━━━━━━━━━━━━━━ THE EVIDENCE Full source list — 122 sources, numbered in the order they appear, with archive copies and dates checked: https://docs.google.com/document/d/1wm66c5wrkKMW-RK8kyQGNF9a1seXfNmSdpq9GOcf9KA/edit?usp=sharing Thumbnail comparisons — 10 pairs, with dates, view counts and the number of days between them: https://docs.google.com/document/d/1uGRbN9gYddOEoeLVNCUzlKhsoCJcB8HFNUy-Jr9-C7w/edit?usp=sharing Dataset — every fern video checked: title matches, topic verdicts: https://docs.google.com/spreadsheets/d/1YOyvQe8cWOlqaK9ejDC95GhKSa_yF3wUCy9ZVI-vHHg/edit?usp=sharing ━━━━━━━━━━━━━━━━━━━━━━━━ METHOD We compared titles, topics, dates and thumbnails. We did not compare scripts, except for the one video they accused us of copying — both scripts went through Copyleaks, and the report is in the sources. All dates were read off the video pages, not off search results. All company figures come from Companies House and the Dutch KVK register. Where a calculation is ours and not theirs, we say so in the film. We watched 17 of fern's 138 films. There are 121 we didn't open. If we got something wrong, tell us and we'll correct it here. ━━━━━━━━━━━━━━━━━━━━━━━━ CORRECTIONS TO OUR OWN FILM Our video "The Man Who Escaped Auschwitz" contains three errors, documented in full under that video: 1. The figure of 1,750,000 stands without the modern estimate beside it. Historians now put it at around 1.1 million murdered at Auschwitz, out of roughly 1.3 million deported. 2. A scene shows prisoners burning a pile of toys. It did not happen in that form. 3. "No one ever escaped to tell the world" is incorrect. Witold Pilecki escaped in April 1943. Source: Auschwitz-Birkenau State Museum — auschwitz.org ━━━━━━━━━━━━━━━━━━━━━━━━ MORE FROM LUME Join our Discord community: /discord Watch our movie channel: /@lumz-cinema Our production studio: https://lume-studio.ai/ Advertising & Business Inquiries: collaboration@lumz.ai ━━━━━━━━━━━━━━━━━━━━━━━━ #fern #Lume #YouTube #AI #Documentary

Who uses it

Real use cases, no hype
API Documentation Hub
Generate and maintain beautiful, interactive API reference docs from OpenAPI or gRPC specs, ensuring they never drift from the source.
SDK Generation & Maintenance
Automatically produce idiomatic client libraries in 8+ languages from a single spec, reducing engineering hours and ensuring consistency.
Developer Portal with AI Support
Build a developer-facing portal with built-in AI chat (Ask Fern) that answers questions grounded in your docs, reducing support load.
Agent-Ready API Exposure
Serve structured API context via llms.txt and an MCP server so AI coding agents (like Cursor, Copilot) can understand and use your API.
Internal Documentation & Knowledge Base
Aggregate documentation from multiple repos into a single, searchable site with role-based access control for internal teams.
Migration from Other Docs Platforms
Move from tools like ReadMe, Mintlify, or custom internal solutions to a unified, spec-driven platform with migration support.
Postman Collection Sync
Generate and keep Postman collections in sync with your API specs and documentation, avoiding manual duplication.
What's great
  • Generates beautiful docs from OpenAPI specs with zero drift
  • AI-native features: llms.txt, MCP server, and Ask Fern chat
  • Generates idiomatic SDKs in 8+ languages from one spec
  • Docs-as-code workflow with Git versioning and PR reviews
  • Enterprise features: RBAC, SSO, SCIM, and custom branding
  • Integrates with postman for collection generation
Technical strengths
  • Built-in MCP server provides live API context to coding agents
Where it falls short
  • Free tier limited to 10 team members and 1,000 pages
  • AI credit usage (250/month) may be restrictive for high-volume sites
  • Advanced customization (custom React, layouts) is Enterprise-only
  • Self-hosting and dedicated infrastructure are Enterprise-only
  • Complex projects may require OpenAPI expertise to configure properly
Technical limitations
  • AI search relies on RAG indexing, which may have latency on large sites
  • Protocol support is broad but some advanced gRPC/Protobuf features may need config
For technical folks

The deep-dive specs

FAQ

Includes technical Q&A
No. Fern is a platform for your entire developer experience: documentation, SDK generation in 8+ languages, and a CLI. All are generated from your API spec (like OpenAPI) as a single source of truth.

Traffic Insights

Monthly Visits

—

November 2026

Growth Rate

0%

vs last month

Dominance

0%

in Coding

Top Country

—

Top Countries Breakdown

—

Growth Trend

Stable

Traffic has remained stable.

Honest pricing

No sneaky tiers, no “contact sales”

Here's who each plan is actually for — and where the hidden charges might hit.

Free
Most picked
Free

Individuals

  • 10 team members
  • 1000 pages
  • 250 AI credits per month
  • 2000 page generations per month
  • Custom domain and subpath
Enterprise
Custom

Enterprise

  • Everything in Free
  • plus: SSO
  • SCIM
  • and advanced RBAC
  • Multiple repos and docs instances
  • Custom CSS
  • JavaScript
View Full Plans & Pricing on Fern

Official pricing, checkout, and plan upgrades are handled directly on buildwithfern.com.

Reviews

What the internet actually thinks

Data refreshed weekly. No paid placements.

Trustpilot
Not reviewed yet
G2
G2
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C
Capterra
Not reviewed yet
Product Hunt
Not reviewed yet
COMMUNITY COMMENTS

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