Shopify Checkout UI Extensions

Before writing code

Fetch live docs:

1. Fetch https://shopify.dev/docs/apps/build/checkout for checkout extensions
2. Web-search site:shopify.dev checkout ui extension targets for available targets
3. Web-search site:shopify.dev checkout ui components for UI primitives

What Are Checkout UI Extensions

Client-side extensions that add UI to Shopify's checkout:

• Render at specific extension targets (locations in checkout flow)
• Use Shopify's UI primitives (not Polaris, not HTML)
• Built with Preact and Remote DOM — sandboxed rendering
• Access checkout state via APIs (no direct DOM access)

Important: You cannot replace Shopify's checkout — only extend it at designated points.