Fern
Generate SDKs in 8+ languages and Stripe-style docs from your OpenAPI spec.
About
Fern is an API developer-experience platform that turns an OpenAPI or AsyncAPI definition into production-grade client SDKs in 8+ languages plus a Stripe-style documentation website. The SDKs are type-safe and idiomatic with automatic pagination, retries, and OAuth handling, and Fern publishes them straight to npm, PyPI, Maven, and other registries. The docs side offers an interactive API playground, custom domains and branding, versioning via Git, WebSocket and SSE support, and an AI-powered search assistant. The generators are open source on GitHub.
The honest picture: Fern is priced for API-first companies — SDK generation starts at $250/month per SDK and documentation at $400/month on the Basic tiers. That is hard to justify for internal-only APIs or side projects, where Mintlify, Scalar, or hand-rolled docs remain the pragmatic choice.
What it can do
- SDK generation in 8+ languages
- Stripe-style API documentation websites
- Auto-publishing to package registries
- Interactive API playground
- AI-powered docs search
- WebSocket and webhook support
Setup
Define your API in OpenAPI; run Fern's CLI or connect via GitHub to generate SDKs and docs.
Prerequisites
An OpenAPI or AsyncAPI specification for your API.
Use cases
Works with
Trust score — 7/10
Scored 7/10 (metrics tier, metrics-v1). Evidence: Verified via vendor site/docs/GitHub and reputable coverage, wave 50; Trending score 69/100 from researcher assessment.
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.