# Fern

**Canonical:** https://apis.io/providers/fern/  
**APIs profiled:** 1

Fern is an SDK generation and documentation platform designed for the AI era. It transforms OpenAPI, AsyncAPI, Protobuf (gRPC), and OpenRPC specifications into idiomatic, production-ready SDKs across nine languages plus auto-generated, branded developer documentation, an AI-first CLI, llms.txt for agent discoverability, Ask Fern AI search, and an MCP server that connects Claude, Cursor, and Windsurf into the workflow. Engineering teams at ElevenLabs, Deepgram, Square, Webflow, Auth0, LaunchDarkly, Cohere, Pinecone, Cash App, and OpenRouter use Fern to deliver world-class developer experiences from a single source of truth.

## Kin Score — 36.2 / 100 (thin)

Scored 2026-08-20 under rubric 0.12.0. Trend: flat (+0.0 from 36.2).

| Facet | Score |
|---|---|
| Discoverability | 59.3 |
| Contract Quality | 11.3 |
| Governance | 25.0 |
| Contract Governance | 25.0 |
| Operational Transparency | 10.5 |
| Developer Ergonomics | 42.9 |
| Commercial Clarity | 72.4 |
| Access Clarity | 72.4 |

## Agent readiness — 7.1 (agent-aware)

| Dimension | Value |
|---|---|
| Spec Presence | no |
| Agentic Access | no |
| Reversibility Documented | no |
| MCP Server | documented |
| Auth Clarity | no |
| Idempotency | no |
| Error Semantics | no |
| OpenAPI Examples | no |
| Rate Limit Signal | documented |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |

## Access

Freemium — onboarding: unknown, pricing: freemium, trial: no (confidence: medium).

## APIs (1)

- **Fern** — Fern transforms a single API source of truth (OpenAPI, AsyncAPI, Protobuf, OpenRPC, or the Fern Definition Language) into type-safe SDKs in nine languages, branded interactive d...

## MCP servers (1)

- **Fern MCP Server**

## Security (1)

- **Fern Domain Security** — TLSv1.3 · HSTS · DMARC

## Plans (1)

- **Fern Plans Pricing**

## Use cases (7)

- **SDK Generation from OpenAPI** — Transform OpenAPI specifications into idiomatic client libraries across nine programming languages with automated publishing to npm, PyPI, Maven Central, NuGet, and other regist...
- **Developer Documentation Hosting** — Replace Docusaurus, Mintlify, GitBook, or ReadMe with a Fern-hosted docs site featuring custom branding and domain.
- **API-First Development** — Define APIs in Fern Definition Language and generate server stubs, SDKs, and documentation from one source of truth.
- **SDK Maintenance Automation** — Auto-update and re-publish SDKs each time an OpenAPI specification changes via GitHub Actions CI/CD.
- **Agent-Ready Documentation** — Make docs consumable by LLMs and AI coding agents through llms.txt, MCP, and structured semantic content.
- **Multi-Protocol Reference Docs** — Document REST plus WebSocket plus gRPC surfaces in a single unified developer experience.
- **Migration From Stainless, ReadMe, Mintlify, or GitBook** — Migrate existing developer docs and SDK pipelines to Fern in days rather than quarters.

## Tags

Agent Ready, Artificial Intelligence, API Definitions, AsyncAPI, Code Generation, Developer Experience, Developer Portal, Documentation, gRPC, llms-txt, MCP, OpenAPI, OpenRPC, Platform, Protobuf, SDK, WebSockets

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/fern/). Scores are computed from the provider's own public artifacts under a published rubric.