Develop Shopify Apps, Themes, and Extensions

Shopify Development Skill covers the full range of Shopify platform development: apps, checkout/admin/POS UI extensions, Liquid themes, GraphQL/REST API integration, webhooks, billing, metafields, and Shopify Functions. Its first job is routing: it decides what to build based on the request - an App for integrating external services, merchant tools, or paid features; an Extension for checkout customization, admin UI, POS actions, or discount rules; a Theme for storefront or product/collection page changes; or an App+Theme Extension combination when both backend logic and storefront UI are needed.

Use it for any Shopify-specific development task: scaffolding an app or theme via the Shopify CLI, writing GraphQL queries and mutations against the 2026-01 Admin API, building a checkout UI extension in React, writing Liquid templates, configuring webhooks - including the GDPR-mandatory data-request, customer-deletion, and shop-deletion endpoints required for app approval - or setting access scopes in shopify.app.toml. It routes to its own reference files for depth rather than covering everything inline - app-development.md for OAuth and billing, extensions.md for UI extension types and Shopify Functions, themes.md for Liquid syntax and theme structure. As with any skill in this set, it is scoped to tasks that clearly match Shopify development, is not a substitute for environment-specific testing, and should pause for clarification when scopes, credentials, or success criteria are not given.

Input: a description of the Shopify feature to build - app, extension, theme, or a combination - plus the access scopes it needs. Output: scaffolding commands (shopify app init, shopify app generate extension --type <type>, shopify theme init), working GraphQL queries and mutations (product and order queries, a metafieldsSet mutation), a webhook configuration block including the mandatory GDPR endpoints, and example extension/theme code such as a React checkout UI block or a Liquid product-card snippet.

mutation SetMetafields($metafields: [MetafieldsSetInput!]!) {
  metafieldsSet(metafields: $metafields) {
    metafields {
      id
      namespace
      key
      value
    }
    userErrors {
      field
      message
    }
  }
}

It also carries built-in troubleshooting playbooks - rate-limit errors (exponential backoff, bulk operations, watching the X-Shopify-Shop-Api-Call-Limit header), failed authentication (token/scope/OAuth checks), extensions not appearing (target, deploy, install checks), webhooks not firing (public URL, HMAC signature, Partner Dashboard logs), and failing GraphQL queries (schema validation, deprecated-field checks) - plus best-practice guidance on API usage, security (HMAC verification, OAuth CSRF state, minimal scopes, session tokens for embedded apps), and performance (response caching, lazy-loaded extensions, image optimization).

Developers building on the Shopify platform - apps, checkout/admin/POS extensions, or Liquid themes - who want the right architecture decision made up front (app vs. extension vs. theme) plus validated GraphQL patterns, webhook setup including GDPR compliance, and a troubleshooting reference for the most common integration failures.