Checkout extensibility
Checkout extensibility: Shopify's framework for customizing checkout with apps and UI extensions, which replaced checkout.liquid and Additional scripts.
What does it mean for shipping protection?
Protection apps use checkout UI extensions to show their offer inside Shopify checkout or on post-purchase pages. Extensions in the information, shipping and payment steps are available only to Shopify Plus stores; extensions on the thank-you and order status pages are available on most plans.
What did it replace?
checkout.liquid and the Additional scripts box. Shopify sunset them on the Thank you and Order status pages on August 28, 2025, and script tags on those pages stopped on August 26, 2026 for non-Plus stores. Old custom-code widgets there may no longer show.
Example
A Shopify Plus store adds a protection toggle directly in the checkout’s order summary using a checkout UI extension, while a store on another plan shows it in the cart and on the thank-you page.
Read how to add shipping protection to Shopify, the shipping protection guide, and see Sam Shipping Protection.
Learn more: Shipping protection guide → · Post-purchase upsell · Thank-you page extension