Shopify Developer Reference

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

Quick Reference

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

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