# Modules SDK

## Overview

The Modules SDK is an open source JavaScript client that provides core functionality for using **existing** [eligibility](https://docs.hatsprotocol.xyz/for-developers/hats-protocol-for-developers/eligibility-modules), [toggle](https://docs.hatsprotocol.xyz/for-developers/hats-protocol-for-developers/toggle-modules) and [hatter](https://docs.hatsprotocol.xyz/hats-protocol-for-developers/hat-admins-and-hatter-contracts#hatter-contracts) Modules and is designed to work both in the browser and in Node.js.

The available Modules are included in the [Modules registry](https://docs.hatsprotocol.xyz/for-developers/hats-modules/building-hats-modules/modules-registry) - an open source registry (currently hosted on GitHub) which contains the various Hats Modules which are available to use.

For documentation about creating new Hats Modules, click [here](https://docs.hatsprotocol.xyz/for-developers/hats-modules/building-hats-modules).

{% content-ref url="modules-sdk/getting-started" %}
[getting-started](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/getting-started)
{% endcontent-ref %}

{% content-ref url="modules-sdk/get-available-modules" %}
[get-available-modules](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/get-available-modules)
{% endcontent-ref %}

{% content-ref url="modules-sdk/create-new-instance-s" %}
[create-new-instance-s](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/create-new-instance-s)
{% endcontent-ref %}

{% content-ref url="modules-sdk/composing-modules" %}
[composing-modules](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/composing-modules)
{% endcontent-ref %}

{% content-ref url="modules-sdk/interact-with-instances" %}
[interact-with-instances](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/interact-with-instances)
{% endcontent-ref %}

{% content-ref url="modules-sdk/utilities" %}
[utilities](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/utilities)
{% endcontent-ref %}

{% content-ref url="modules-sdk/types" %}
[types](https://docs.hatsprotocol.xyz/for-developers/hats-modules/modules-sdk/types)
{% endcontent-ref %}