Preview changes locally

View and share updates to your documentation

Fern offers two ways to preview changes to your documentation: a local development environment and unique preview links.

Local development

Fern allows you to view changes to your documentation in a locally-hosted environment.

Prerequisite: Please install Node.js (version 18 or higher) before proceeding.

Follow these steps to install and run the Fern CLI:

Step 1: Install the Fern CLI:

$npm i -g fern-api

Step 2: Navigate to the docs directory (where the fern folder is located) and execute the following command:

$fern docs dev

A local preview of your documentation will be available at http://localhost:3000. The functionality is available offline if you have run local development mode online at least once.

Some features (e.g. search) are disabled in the local development environment.

Custom ports

By default, Fern uses port 3000. You can customize the port Fern runs on by using the --port flag. For example, to run Fern on port 3002, use this command:

$fern docs dev --port 3333

If you attempt to run Fern on a port that’s already in use, it will use the next available port:

Fern allows you to generate a shareable preview link displaying the current state of your docs. Each preview link is appended with a UUID and is not indexed. Currently, these links do not expire (this behavior is subject to change in the future).

Usage:

$fern generate --docs --preview

Example:

$fern generate --docs --preview
>
>[docs]: Found 0 errors and 1 warnings. Run fern check --warnings to print out the warnings.
>[docs]: Published docs to https://fern-preview-a1da0157-93ca-4b1f-b310-8dd34fb891ca.docs.buildwithfern.com
>┌─
>│ ✓  docs.example.com
>└─