Fern Docs
Docs, SDKs, and CLI from one API spec, built for the AI era
Fern is a strong choice for API-first teams that want docs, SDKs, and CLI generation integrated with AI-readiness (llms.txt, MCP server, AI chat). If you don't need SDK generation or AI features, simpler tools like ReadMe or Mintlify may be more cost-effective. The Hobby tier is free and covers 2 team members, making it easy to evaluate.
- API-first companies wanting AI-ready docs, SDKs, and CLI from one source of truth
- Teams migrating from ReadMe, Mintlify, or Stainless
- Developers needing multi-language SDKs alongside documentation
- Organizations requiring self-hosting, SSO, and localization
- Teams that only need basic static documentation without SDK/CLI generation
- Small projects or startups without budget for enterprise features
- Users preferring a no-code documentation builder without Git workflows
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Skip Fern if you only need basic static docs without SDK/CLI generation or AI agent compatibility and prefer a simpler tool like ReadMe or Mintlify.
Going beyond 250 AI credits on the Hobby plan requires upgrading to Team ($150/mo yearly) or Enterprise.
Fern's Hobby tier ($0/mo) is generous for individuals getting started. At $150/mo (yearly) for 5 team members and 1,000 AI credits, Team is competitively priced versus Mintlify (Pro at ~$160/mo for similar limits). Enterprise is custom but includes migration services, SLAs, and self-hosting, making it cost-effective for large teams scaling AI-ready docs. For very small static-only needs, ReadMe's free tier has no team or credit limits.
In short
Fern Docs — Docs, SDKs, and CLI from one API spec, built for the AI era. Best for API-first companies wanting AI-ready docs, SDKs, and CLI from one source of truth, Teams migrating from ReadMe, Mintlify, or Stainless, Developers needing multi-language SDKs alongside documentation. Free to start; paid plans from $150/mo.
What's new in Fern Docs
Checked 9 days agoAcross the latest 7 updates: 3 feature updates, 1 launch and 3 news mentions.
Our largest docs sites now render ~6.4x faster
Rebuilt storage so a one-page edit only touches one page, improving render speed 6.4x.
CLI vs MCP: which API interface should you build first? (June 2026)
Educational comparison of CLI vs MCP interface for API access.
When to use MCP vs a CLI for API access: a practical guide (June 2026)
Practical guide on choosing between MCP and CLI for API access.
Introducing Fern Replay
Replay reapplies SDK customizations on every regeneration automatically across all languages.
Migrate from Stainless today
Comparison of Fern vs Stainless SDK generators: 9+ languages, WebSockets, gRPC, CLI, on-prem.
We built a CLI generator for agents and humans
Generate CLI from same API spec as Docs/SDKs, now in early access.
How we built Agent Score to improve Fern Docs
Built Lighthouse-style benchmark for AI-agent readiness and shipped fixes publicly.
Viability Score
How likely is Fern Docs to still be operational in 12 months? Based on 4 signals — momentum (how recently it shipped), wrapper dependency, revenue model, and web presence.
Last calculated: July 2026
How we score →Key Features
- Generate docs from OpenAPI, GraphQL, gRPC, Protobuf specs
- Generate idiomatic SDKs in 9+ languages
- Agent-first CLI generation (early access)
- AI chat grounded in documentation
- llms.txt auto-generation for LLM compatibility
- MCP server for real-time AI tool queries
- AI-assisted authoring via Fern Writer (Slack/Teams)
- Docs as code with Git versioning and PR workflows
- Multi-source doc aggregation from multiple repos
- Localization support for translated content
- Self-hosting option for enterprise security
- SAML/OIDC and RBAC access control
- Native Postman collection generation
- SOC 2 Type II compliance
- Fern Replay (auto-reapply SDK customizations on regeneration)
About Fern Docs
Fern generates beautiful, customizable documentation websites, idiomatic SDKs in 9+ languages, and an agent-first CLI from a single API spec. Designed for API-first companies and engineering teams, Fern integrates AI chat grounded in docs, auto-generates llms.txt for LLM compatibility, and provides an MCP server for real-time AI tool queries. It supports modern API protocols including REST, WebSockets, GraphQL, gRPC, and Protobuf. Key features include docs-as-code with Git versioning, multi-source aggregation from multiple repos, localization, self-hosting, and native Postman collection generation. Security includes SAML/OIDC access control and SOC 2 Type II compliance. Fern also offers AI-assisted authoring via Fern Writer (Slack/Teams) and Fern Replay, which auto-reapplies SDK customizations on regeneration. With over 20 million docs pages served per year and a 99% reduction in time to first API call, Fern is built for teams that need AI-ready documentation, SDKs, and CLI from one source of truth. Unlike alternative tools like ReadMe or Mintlify which focus primarily on documentation, Fern uniquely combines docs, SDKs, and CLI generation with AI-readiness, making it ideal for teams that want to future-proof their developer experience.
Behind the Verdict
Fern stands out because it treats docs, SDKs, and CLI as a single product, not separate concerns. For API-first teams shipping multi-language SDKs and agent-compatible docs, this is a time-saver. The AI features—llms.txt, MCP server, AI chat—feel genuinely useful, not gimmicks. In practice, we'd reach for Fern when we need SDK generation alongside docs and want AI-readiness out of the box. Where it bites: the free Hobby tier limits you to 2 team members and 250 AI credits. Scaling to Team ($150/mo yearly) jumps to 5 members and 1,000 credits, which may feel steep for small teams. Compared to Mintlify or ReadMe, Fern offers SDKs and CLI generation—those are its killer features. If you only need documentation, Fern is overkill. One caveat: the CLI generator is still in early access, so expect rough edges. The recent 6.4x render speed improvement (July 2026) makes larger doc sites snappier. Fern Replay (May 2026) is a solid addition for teams that customize SDKs and want those customizations to survive regeneration. Overall, Fern is best for API companies shipping to developers—think Stripe or Twilio wannabes—not for internal docs or small projects.
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Real-world workflow fit
Concrete scenarios for the personas Fern Docs actually fits — and what changes day-one when you adopt it.
You have an OpenAPI spec and want to ship docs, an SDK (e.g., Python), and a CLI with minimal effort.
Outcome: Run 'fern generate' to produce a docs site, Python SDK, and CLI binary from the same spec, published in minutes.
Your team uses multiple GitHub repos for code and docs, and you need a unified documentation site with version switching.
Outcome: Aggregate content from three repos into one Fern site, deploy via GitHub Actions, and serve versioned docs for v1 and v2 simultaneously.
Use Cases
- Generate SDKs in 9+ languages from a single OpenAPI spec to reduce maintenance overhead.
- Create an MCP server for your API so AI coding agents can interact with your endpoints in real time.
- Manage documentation as code with Markdown files versioned in Git and deployed via CI/CD.
- Use Fern Writer in Slack to request documentation updates that automatically open GitHub PRs.
- Aggregate docs from multiple GitHub repos into one unified site with product and version switching.
- Get an Agent-readiness score for your docs and improve AI-friendliness using Agent Score.
- Migrate from ReadMe, Mintlify, or Stainless to Fern for unified SDKs and agent-friendly docs.
- Self-host docs for stricter security, networking, and compliance requirements.
Limitations
- The CLI generator is in early access, and some advanced features like custom AI search and self-hosting require an Enterprise plan.
- The documentation is primarily aimed at developers familiar with API specs.
as of 2026-06-28
12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
Plans compared
For each published Fern Docs tier: who it actually fits, and what it adds vs. the previous tier. Cross-reference the cost calculator above for projected annual outlay.
Hobby
$0/mo
Ideal for
Solo developer or small team exploring Fern, with up to 2 members and 250 AI credits.
What this tier adds
Free entry point with 2 team members, 250 AI credits, custom domain, and basic features; includes Fern branding and 1 site.
Team
$150/mo (yearly)
Ideal for
Growing team of up to 5 members that needs more AI credits (1,000) and version switching.
What this tier adds
Adds 5 team members, 1,000 AI credits, custom subpath, product/version switching, password-protected docs, PDF exports, and email support.
Enterprise
Custom
Ideal for
Large organizations requiring self-hosting, SSO, RBAC, localization, and dedicated support.
What this tier adds
Adds visitor authentication (JWT, SSO), RBAC, translated content, self-hosting, enterprise SSO, dedicated Slack/Teams channel, and custom SLAs.
Where the pricing makes sense
The company stage and team size where Fern Docs's pricing actually pencils out — and where peers do it cheaper.
Fern's Hobby tier ($0/mo) is generous for individuals getting started. At $150/mo (yearly) for 5 team members and 1,000 AI credits, Team is competitively priced versus Mintlify (Pro at ~$160/mo for similar limits). Enterprise is custom but includes migration services, SLAs, and self-hosting, making it cost-effective for large teams scaling AI-ready docs. For very small static-only needs, ReadMe's free tier has no team or credit limits.
Setup time & first value
How long it actually takes to get something useful out of Fern Docs — broken out by persona, not the marketing-page minute.
For an individual developer: ~10 minutes to connect your OpenAPI spec and generate a docs site. For a team: ~1-2 hours to set up multi-repo aggregation, configure custom domain, and enable CI/CD with GitHub Actions. Enterprise migrations (from ReadMe, Mintlify) take 1-2 weeks with Fern's migration services.
Switching to or from Fern Docs
How to bring data in from common predecessors and how to get it back out — written for the switcher, not the buyer.
- →From ReadMe: Fern handles migration with dedicated support, porting API reference and markdown content.
- →From Mintlify: Fern migrates docs while adding WebSocket SDK support and agent-friendly features.
- →From Stainless internal SDK: Fern unifies SDKs and docs from one spec, eliminating dual maintenance.
- ↗To ReadMe or Mintlify: Export Fern markdown content and use their import tools; SDKs and CLI will need separate regeneration.
- ↗To a custom static site (e.g., Docusaurus): Export your .mdx files and rebuild navigation manually.
Integrations
Resources & Guides
Official links
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Common stack mates teams adopt alongside Fern Docs, with the specific reason each pairing earns its keep.
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