Fern | Introduction to the Fern toolkit for REST APIs

Fern is a toolkit for building REST APIs. With Fern, you can generate SDKs, API documentation, and boilerplate for your backend server.

Fern is fully compatible with OpenAPI. Leverage your existing OpenAPI specification to generate code and documentation through Fern. If you’re not a fan of OpenAPI, you can also use Fern’s simpler format to define your API.

Overview of Fern

Overview of Fern

Fern’s Magic 🪄

The magic of Fern is our compiler, which transforms your API definition into:

  • SDKs. Client libraries that feel handwritten and are published to package managers like npm and PyPI.
  • Documentation. A beautiful docs website with a best-in-class API Reference. Automatically sync your Postman Collection.
  • Backend boilerplate. Server side code, such as Pydantic models for FastAPI and Jersey interfaces for Spring Boot. Get compile-time validation that your endpoints are being served correctly.