# Overview (/docs/sdks/fastify-backend)

Protect Fastify APIs with MonoCloud access token validation.

Use it to:

- Validate JWT and opaque access tokens
- Protect API routes globally or individually
- Enforce scope and group-based authorization
- Validate mTLS certificate-bound tokens

## Install the SDK [#install-the-sdk]

Install the SDK using your package manager:

```npm title="Terminal"
npm install @monocloud/backend-node
```

View the source on GitHub: [monocloud/auth-js](https://github.com/monocloud/auth-js)

## Get started quickly [#get-started-quickly]

Start with the quickstart to see MonoCloud in action:

- [Fastify Quickstart](/docs/quickstarts/fastify-backend)

The quickstart walks you from a new Fastify app to a protected Fastify API.

## Before you continue [#before-you-continue]

To integrate MonoCloud into your own app:

1. Follow the [installation and configuration guide](/docs/sdks/fastify-backend/installation).
1. Use the guides below to secure different parts of your API.

## Guides [#guides]

- [Protect API routes](/docs/sdks/fastify-backend/protect-api) — Protect routes globally or individually with scopes and groups
- [Introspect Access Tokens](/docs/sdks/fastify-backend/introspection) — Validate tokens via the authorization server's introspection endpoint
- [Validate mTLS Bound Tokens](/docs/sdks/fastify-backend/mtls-binding) — mTLS certificate-bound token validation
- [Customize the client](/docs/sdks/fastify-backend/custom-client) — Create a custom client to share across hook instances
- [Add a custom cache](/docs/sdks/fastify-backend/custom-cache) — Cache introspection results to reduce validation overhead

## API Reference [#api-reference]

View all exported APIs, types, and interfaces:

- [Backend Node SDK API Reference](https://monocloud.github.io/auth-js/modules/_monocloud_backend-node.html)