Theme Check is a linter for the Liquid and JSON inside your theme and [theme app extensions](/docs/apps/build/online-store/theme-app-extensions). It detects errors and enforces Liquid best practices.

Theme Check can identify several issues in your theme code. For example, it can identify the following:

* Syntax errors
* Missing templates
* Unused variables and snippets
* Unknown and deprecated tags
* Performance issues

Programming and style errors display directly in your console or code editor. Each error includes a link to the failed check's documentation, allowing you to debug issues quickly.

You can use Theme Check in the following ways:

* **Through Shopify CLI** - Run checks against your theme on demand, in CI or with our Language Server.
* **Via the Shopify Liquid Visual Studio Code extension** - Theme Check is included in the extension.

## Installation

* [Install Theme Check with Shopify CLI](/docs/api/shopify-cli)
* [Install the Shopify Liquid Visual Studio Code extension](/docs/storefronts/themes/tools/cli/language-server)

## Configuration

You can configure check options to override defaults, or enable or disable specific checks, or point to your own [custom checks](#creating-your-own-checks). To learn more, refer to [Theme Check configuration](/docs/storefronts/themes/tools/theme-check/configuration).

## Creating your own checks

You can write your own checks in TypeScript and then reference them in your [configuration](/docs/storefronts/themes/tools/theme-check/configuration). To learn about how the existing checks are written, explore the [`theme-tools` repo](https://github.com/Shopify/theme-tools/blob/main/docs/theme-check-common/writing-your-own-check).

## Using Theme Check in other editors

Theme Check is available for integration in other editors using Shopify's [Language Server](/docs/storefronts/themes/tools/cli/language-server).

## Command reference

  <div>
  <a class="resource-card" href="/docs/storefronts/themes/tools/theme-check/checks" data-theme-mode="">
    <div class="resource-card__indicator-container"><img
     src="/assets/resource-cards/docs"
     data-alt-src="/assets/resource-cards/docs-dark"
     aria-hidden="true"
     class="resource-card__icon themed-image"></div>
    <h3 class="resource-card__title">
      Checks reference
    </h3>
    <p class="resource-card__description">Learn what each check does, how to configure it, and when to disable it.</p>
  </a>
</div>


  <div>
  <a class="resource-card" href="/docs/storefronts/themes/tools/theme-check/commands" data-theme-mode="">
    <div class="resource-card__indicator-container"><img
     src="/assets/resource-cards/docs"
     data-alt-src="/assets/resource-cards/docs-dark"
     aria-hidden="true"
     class="resource-card__icon themed-image"></div>
    <h3 class="resource-card__title">
      Command reference
    </h3>
    <p class="resource-card__description">Review the Theme Check reference for commands.</p>
  </a>
</div>


## Contributing to Theme Check

Theme Check is open source and part of our suite of theme developer tools.

* Learn how to contribute to the [theme-tools repository](https://github.com/Shopify/theme-tools/blob/main/docs/contributing.md)