# Libraries & SDKs

Choose the right library for your environment. All libraries are built on the [REST API](https://bkper.com/docs/build/scripts/rest-api.md) and are used by the Bkper team to build our own products.

## bkper-js

**JavaScript/TypeScript SDK for Node.js and browsers.**

The primary client library for programmatic access to Bkper. Use it for [scripts](https://bkper.com/docs/build/scripts/node-scripts.md), [platform apps](https://bkper.com/docs/build/apps/overview.md), and web applications.

```ts
import { Bkper } from 'bkper-js';
import { getOAuthToken } from 'bkper';

Bkper.setConfig({
    oauthTokenProvider: async () => getOAuthToken(),
});

const bkper = new Bkper();
const books = await bkper.getBooks();
```

- [npm package](https://www.npmjs.com/package/bkper-js)
- [API Reference](https://bkper.com/docs/api/bkper-js.md)

## bkper-gs

**Google Apps Script library.**

Access Bkper from Apps Script — Google Sheets automations, triggers, add-ons. Authentication is handled by the Apps Script runtime.

```js
function listBooks() {
    var books = BkperApp.getBooks();
    books.forEach(function (book) {
        Logger.log(book.getName());
    });
}
```

- [GitHub](https://github.com/bkper/bkper-gs)
- [API Reference](https://bkper.com/docs/api/bkper-gs.md)

## @bkper/web-auth

**Web authentication SDK for the Bkper Platform.**

Browser-based OAuth for apps hosted on `*.bkper.app` subdomains. Use with bkper-js when building platform apps.

```ts
import { BkperAuth } from '@bkper/web-auth';

const auth = new BkperAuth({ onLoginSuccess: () => initApp() });
await auth.init();

// Use with bkper-js
const token = await auth.getAccessToken();
```

- [npm package](https://www.npmjs.com/package/@bkper/web-auth)
- [API Reference](https://bkper.com/docs/api/bkper-web-auth.md)

## @bkper/web-design

**CSS design tokens for Bkper web applications.**

Provides typography, spacing, border, and color tokens as CSS custom properties. Includes light/dark theme support and account-type color families. Works standalone or integrates with [Web Awesome](https://www.webawesome.com/) — if Web Awesome is loaded, Bkper tokens automatically inherit its design system values.

```css
@import '@bkper/web-design';
```

Then use the tokens in your styles:

```css
.my-component {
    font-family: var(--bkper-font-family);
    padding: var(--bkper-spacing-medium);
    color: var(--bkper-color-text);
    border: var(--bkper-border);
}
```

- [npm package](https://www.npmjs.com/package/@bkper/web-design)
- [Token Reference](https://bkper.com/docs/api/bkper-web-design.md)

## @bkper/bkper-api-types

**TypeScript type definitions for the REST API.**

Add autocomplete and contextual documentation to any TypeScript project that works with Bkper API payloads.

```bash
npm install @bkper/bkper-api-types
```

Configure `tsconfig.json` to make the `bkper` namespace globally available:

```json
{
    "compilerOptions": {
        "types": ["@bkper/bkper-api-types"]
    }
}
```

Then use the `bkper` namespace directly — no import needed:

```ts
const event: bkper.Event = await c.req.json();
if (!event.book) {
    throw new Error('Missing book in event payload');
}
const book: bkper.Book = event.book;
```

- [npm package](https://www.npmjs.com/package/@bkper/bkper-api-types)
- [API Reference](https://bkper.com/docs/api/bkper-api-types.md)

## Which library to use

| Scenario                                       | Library                                                            |
| ---------------------------------------------- | ------------------------------------------------------------------ |
| Node.js scripts and automations                | bkper-js + CLI                                                     |
| Browser (any domain, with access token)        | [bkper-js via CDN](https://github.com/bkper/bkper-js#cdn--browser) |
| Platform apps (server-side)                    | bkper-js                                                           |
| Platform apps (client-side, \*.bkper.app only) | bkper-js + @bkper/web-auth                                         |
| Platform apps (styling)                        | @bkper/web-design                                                  |
| Google Apps Script                             | bkper-gs                                                           |
| Google Sheets add-ons                          | bkper-gs                                                           |
| Any language (direct HTTP)                     | [REST API](https://bkper.com/docs/build/scripts/rest-api.md) + @bkper/bkper-api-types  |