Yes. Fern is open source under the Apache-2.0 licence. Its source code is on GitHub at fern-api/fern and is written mainly in TypeScript.

Yes. Fern is open source, so the software itself is free to use.

Can I self-host Fern?

Yes. Fern can be self-hosted on your own server or infrastructure.

What is Fern an alternative to?

Fern is an open-source alternative to APIMatic. Other open-source alternatives to APIMatic include Cortex Docs, OpenAPI Generator and Scalar.

Is Fern actively maintained?

Yes. The most recent commit to Fern was on 14 October 2026, and the latest release is 5.23.3, published on 12 May 2026. The project has 3.8k stars on GitHub.

Fern (fern-api/fern): open-source alternative to APIMatic

About Fern

Fern is a tool that takes an OpenAPI specification as input and produces SDKs in multiple languages, interactive API documentation, and an agent-first CLI. It is designed for API providers who want to offer ready-to-use client libraries and documentation.

Key features

Generates SDKs in multiple languages from an OpenAPI spec
Produces interactive API documentation
Creates an agent-first CLI

Built with: TypeScript tools
Tags: openapi; sdk-generation; api-documentation; cli; api-tools

Fern: questions and answers

What is Fern?: Fern generates SDKs in multiple languages, interactive API documentation, and an agent-first CLI from an OpenAPI specification.
Is Fern open source?: Yes. Fern is open source under the Apache-2.0 licence. Its source code is on GitHub at fern-api/fern and is written mainly in TypeScript.
Is Fern free?: Yes. Fern is open source, so the software itself is free to use.
Can I self-host Fern?: Yes. Fern can be self-hosted on your own server or infrastructure.
What is Fern an alternative to?: Fern is an open-source alternative to APIMatic. Other open-source alternatives to APIMatic include Cortex Docs, OpenAPI Generator and Scalar.
Is Fern actively maintained?: Yes. The most recent commit to Fern was on 14 October 2026, and the latest release is 5.23.3, published on 12 May 2026. The project has 3.8k stars on GitHub.