Overview | Fern Documentation

The Fern CLI lets you initialize projects, validate API definitions, preview changes locally, and publish documentation and SDKs. This page covers installation and common commands to get you started.

Installation

Install the Fern CLI with npm or Homebrew.

npm

Homebrew

Requires Node.js 22 or higher, which ships with npm 10 or higher. If you’re on an older version, upgrade Node.js.

$ npm install -g fern-api
$ fern -v

Alternative: install as a project dependency

Most users install Fern globally with the commands above. Install it locally instead to pin its version per project or to work in an environment with limited internet connectivity. Local installs use npm. Homebrew supports only system-wide installs.

Add Fern to your project

$ npm install fern-api

Set the version to your local install

In fern.config.json, set the version to *:

fern.config.json

1 {
2   "organization": "your-org",
3   "version": "*"
4 }

The fern.config.json reference covers the remaining fields.

Run commands through npm

$ npm fern check
$ npm fern generate

CLI workflows by product

The Fern CLI manages both documentation and SDK workflows. Below is a brief overview of the common commands for each. All commands support global options like --log-level for debugging.

For complete CLI documentation, see the command reference.

Docs workflow

When working with Fern Docs, you’ll use these CLI commands. For complete instructions, see the Docs quickstart.

Command	Description
`fern init --docs`	Create a new docs project
`fern docs dev`	Preview docs locally at `localhost:3000`
`fern generate --docs`	Publish documentation to production

SDK workflow

When working with Fern SDKs, you’ll use these CLI commands. For complete instructions, see the SDKs quickstart.

Command	Description
`fern init`	Create a new SDK project
`fern check`	Validate your API definition
`fern generate --preview`	Preview SDKs locally in `.preview/`
`fern generate`	Publish SDKs to production
`fern generate --group <name>`	Generate a specific SDK group