Quickstart

Get up and running with Fern in under 5 minutes. This quickstart walks you through installing the CLI, initializing your project, and generating your first SDK locally.

Install the Fern CLI

$ npm install -g fern-api

Initialize the fern folder

Initialize the fern folder with your existing OpenAPI specification. Specify your organization name using the --organization flag.

$ fern init --openapi path/to/openapi.yml \
> --organization <YourOrganization>

OpenAPI accepts both JSON and YAML formats.

This creates a fern folder in your current directory.

fern

fern.config.json# root-level configuration

api# your API

generators.yml# generators you're using

openapi

openapi.yml# API-level configuration

Validate your API definition

Check that your API definition is valid, and fix errors before proceeding:

$ fern check

Generate

fern init includes a TypeScript SDK generator by default. Run fern generate to see it in action:

$ fern generate

This creates a sdks/typescript folder containing your generated SDK:

fern# created by fern init

sdks# created by fern generate

typescript

Client.ts

index.ts

core

api

Next steps

Now that you have a working SDK, set up GitHub repositories and configure publishing, generate SDKs in another languages, or learn more about Fern SDKs.

TypeScript

Set up GitHub, publish to npm, and more.

All languages

See all supported languages, including Python, Go, and Java.

How it works

Understand the Fern SDK generation pipeline.

Project structure

Learn about Fern’s multi-repo file structure and GitHub setup.

$	fern init --openapi path/to/openapi.yml \
>	--organization <YourOrganization>