Shopify Developer Reference

Comprehensive reference for professional Shopify development - API version 2026-01.

Quick Reference

Item	Value
API version	2026-01 (stable)
GraphQL Admin	POST https://{store}.myshopify.com/admin/api/2026-01/graphql.json
Storefront API	POST https://{store}.myshopify.com/api/2026-01/graphql.json
Ajax API (theme)	/cart.js, /cart/add.js, /cart/change.js
CLI install	npm install -g @shopify/cli
Theme dev	shopify theme dev --store {store}.myshopify.com
App dev	shopify app dev
Deploy	shopify app deploy
Docs	shopify.dev

Choose Your Path

Read the reference file(s) that match your task:

Liquid templating - writing or debugging .liquid files:

• references/liquid-syntax.md - Tags, control flow, iteration, whitespace, LiquidDoc
• references/liquid-filters.md - All filter categories with examples
• references/liquid-objects.md - Product, collection, cart, customer, and global objects

Theme development - building or customising themes:

• references/theme-development.md - OS 2.0 architecture, sections, blocks, JSON templates, settings schema

API integration - fetching or modifying data programmatically:

• references/api-admin.md - GraphQL Admin API (primary), REST (legacy), OAuth, webhooks, rate limiting
• references/api-storefront.md - Storefront API, Ajax API, cart operations

App development - building Shopify apps:

• references/app-development.md - Shopify CLI, extensions, Polaris Web Components, App Bridge

Serverless logic - custom business rules:

• references/functions.md - Shopify Functions (replacing Scripts), Rust/JS targets, deployment

Headless commerce - custom storefronts:

• references/hydrogen.md - Hydrogen framework, React Router 7, Storefront API integration

Optimisation and troubleshooting:

• references/performance.md - Images, JS, CSS, fonts, Liquid, Core Web Vitals
• references/debugging.md - Liquid errors, API errors, cart issues, webhook failures

Deprecation Notices

Deprecated	Replacement	Deadline
Shopify Scripts	Shopify Functions	August 2025 (migration), sundown TBD
checkout.liquid	Checkout Extensibility	August 2024 (Plus), done
REST Admin API	GraphQL Admin API	Active deprecation (no removal date yet)
Legacy custom apps	New auth model	January 2025 (done)
Polaris React	Polaris Web Components	Active migration
Remix (app framework)	React Router 7	Hydrogen 2025.5.0+

Liquid Essentials

Three syntax types:

{{ product.title | upcase }}                    {# Output with filter #}
{% if product.available %}In stock{% endif %}   {# Logic tag #}
{% assign sale = product.price | times: 0.8 %}  {# Assignment #}
{%- if condition -%}Stripped whitespace{%- endif -%}

Key patterns:

{% for product in collection.products limit: 5 %}
  {% render 'product-card', product: product %}
{% endfor %}

{% paginate collection.products by 12 %}
  {% for product in paginate.collection.products %}...{% endfor %}
  {{ paginate | default_pagination }}
{% endpaginate %}

API Essentials

// GraphQL Admin - always use GraphQL over REST
const response = await fetch(
  `https://${store}.myshopify.com/admin/api/2026-01/graphql.json`,
  {
    method: 'POST',
    headers: {
      'X-Shopify-Access-Token': accessToken,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ query, variables }),
  }
);
const { data, errors } = await response.json();
if (errors) throw new Error(errors[0].message);

// Ajax API (theme-only cart operations)
fetch('/cart/add.js', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ id: variantId, quantity: 1 }),
});

Reference Files

File	Lines	Coverage
liquid-syntax.md	~600	Tags, control flow, iteration, variables, whitespace, LiquidDoc
liquid-filters.md	~870	String, numeric, array, Shopify-specific, date, URL, colour filters
liquid-objects.md	~695	All Shopify objects: product, variant, collection, cart, customer, order, etc.
theme-development.md	~1200	File structure, JSON templates, sections, blocks, settings schema, layout
api-admin.md	~595	GraphQL queries/mutations, REST (legacy), OAuth, webhooks, rate limiting
api-storefront.md	~235	Storefront API, Ajax API, cart operations, Customer Account API
app-development.md	~760	CLI, app architecture, extensions, Polaris Web Components, deployment
functions.md	~300	Function types, Rust/JS targets, CLI workflow, Scripts migration
hydrogen.md	~375	Setup, routing, data loading, Storefront API, deployment
performance.md	~605	Images, JS, CSS, fonts, Liquid, third-party scripts, Core Web Vitals
debugging.md	~650	Liquid, JavaScript, API, cart, webhook, theme editor troubleshooting