# Client library

### Overview

GitBook provides an official TypeScript/JavaScript client for the [HTTP API](https://gitbook-v2-q67etdj25-gitbook.vercel.app/url/gitbook.com/docs/developers/gitbook-api/api-reference). This client can be used in a browser or Node.js environment. 

### Installation

When [bootstrapping an integration using the GitBook CLI](https://gitbook-v2-q67etdj25-gitbook.vercel.app/url/gitbook.com/docs/developers/quickstart#bootstrap-your-app), the library will be installed by default. If you need to, you can also install the GitBook Node.js library through `npm`.

```bash
npm install @gitbook/api
```

### Initialize the client

To start using the GitBook client library, you’ll first need to initialize the library with your [developer token](https://gitbook-v2-q67etdj25-gitbook.vercel.app/url/gitbook.com/docs/developers/quickstart#create-a-personal-access-token). 

```typescript
import { GitBookAPI } from '@gitbook/api';

const client = new GitBookAPI({
  authToken: <your_access_token>
});
```

#### Usage with Node.js

When using the `@gitbook/api` module with Node.js < v18, you should pass a custom `fetch` function.

You can install one using the [`node-fetch`](https://github.com/node-fetch/node-fetch) module.

```typescript
import { GitBookAPI } from '@gitbook/api';
import fetch from 'node-fetch';

const client = new GitBookAPI({
  customFetch: fetch
});
```