Develop Shopify Apps, Themes, and Extensions

Routes Shopify development to the right build target: an App for integrating external services, merchant tools, or billing; an Extension for checkout/admin UI customization, POS actions, or discount rules; a Theme for storefront design or product/collection page changes; or an App+Theme Extension combination when both backend logic and storefront UI are needed. Installs and drives everything through the Shopify CLI:

npm install -g @shopify/cli@latest

then shopify app init/app dev/app deploy for apps, shopify app generate extension --type for checkout_ui_extension/admin_action/admin_block/pos_ui_extension/function extensions, and shopify theme init/theme dev/theme pull --live/theme push --development for themes.

Access scopes are configured in shopify.app.toml under [access_scopes] as a comma-separated list: read_products/write_products, read_orders/write_orders, read_customers/write_customers, read_inventory/write_inventory, read_fulfillments/write_fulfillments. GraphQL patterns are validated against API version 2026-01: querying products with variants and cursor-based pageInfo.endCursor pagination, querying orders with displayFinancialStatus and totalPriceSet, and a metafieldsSet mutation with an example variables payload writing a custom.care_instructions metafield. A checkout extension example builds a gift-message block with reactExtension("purchase.checkout.block.render", ...), a BlockStack/TextField/Checkbox UI, and useApplyAttributeChange to write a gift_message cart attribute. A Liquid example renders a product-card snippet using img_url, money and escape filters and a compare_at_price sale badge. Webhooks are configured in shopify.app.toml under [[webhooks.subscriptions]] with topics like orders/create/orders/updated/products/update, plus the mandatory GDPR privacy-compliance webhooks (customer data request, customer deletion, shop deletion) required for app approval.

Best practices are grouped under API usage (prefer GraphQL over REST, request only needed fields, cursor-based pagination, bulk operations above 250 items, exponential backoff on rate limits), security (credentials in environment variables, verify webhook HMAC signatures, validate the OAuth state parameter against CSRF, request minimal scopes, use session tokens for embedded apps), and performance (cache infrequently-changing responses, lazy-load in extensions, optimize theme images via img_url, monitor GraphQL query cost via response headers). A troubleshooting section covers rate limits (X-Shopify-Shop-Api-Call-Limit header, bulk operations), auth failures (token validity, granted scopes, OAuth completion), extensions not appearing (target correctness, shopify app deploy, app installed on the test store), webhooks not firing (public URL, HMAC validation, Partner Dashboard logs), and failing GraphQL queries (schema validation via GraphiQL, deprecated fields, access scopes).

Use it for building Shopify apps or extensions, checkout/admin/POS UI customization, Liquid theme development, GraphQL or REST API integration, webhooks, billing, metafields, or Shopify Functions.

Input is the desired Shopify surface, app, extension, or theme, and its target scopes or webhook topics. Output is a scaffolded project via the CLI, GraphQL queries and mutations, extension or theme code, and a configured shopify.app.toml for scopes and webhooks.

Integrates with the Shopify Admin GraphQL API (version 2026-01), Shopify CLI, checkout UI extensions (@shopify/ui-extensions-react/checkout), Liquid themes, and webhooks; ships scripts/shopify_init.py for interactive scaffolding and scripts/shopify_graphql.py for query templates, pagination and rate limiting, plus reference docs for app development, extensions and themes. Points to Shopify's developer docs, GraphQL Admin API reference, CLI reference, and the Polaris design system; the API follows quarterly releases with a 12-month deprecation window.

Developers building Shopify apps, checkout/admin/POS extensions, or Liquid themes who need CLI commands, GraphQL patterns, webhook configuration and troubleshooting steps for the current API version.