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

Checks reference

Learn what each check does, how to configure it, and when to disable it.

Command reference

Review the Theme Check reference for commands.

## 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)