# Checkout extensibility: what Shopify Plus can change now that checkout.liquid is dead

Source: https://deftmerch.com/blog/2026-11-12-shopify-checkout-extensibility-plus.html

DeftMerch answers


**Short answer:** Checkout extensibility is the set of tools that replaced hand-editing the checkout code: the checkout editor, checkout UI extensions, Shopify Functions, and pixels. Checkout UI extensions on the information, shipping, and payment steps work only on Shopify Plus, and the Checkout Branding API is Plus-only. Every plan from Basic up gets the checkout editor and apps on the thank-you and order status pages. Checkout.liquid is gone, and Shopify Scripts stopped on June 30, 2026.

## What checkout.liquid was, and when it died

Checkout.liquid was a layout file that lived inside the theme, and it let Shopify Plus stores edit the checkout's code directly. Because it sat in the theme, a Shopify checkout update could quietly break it, and the merchant owned the breakage. Shopify switched it off in stages: it stopped working on the information, shipping, and payment pages on August 13, 2024, and it was sunset on the thank-you and order status pages on August 28, 2025.

Shopify Scripts went the same way. Scripts were the custom code for discount, shipping, and payment logic, and they stopped executing on June 30, 2026. Discount, delivery, and payment logic now runs on Shopify Functions, and the Functions that do the work are the replacement, not the equivalent: they run in a Shopify-hosted sandbox, and Shopify updates the checkout around them.

The additional scripts box became view-only on August 28, 2025, and the non-Plus deadline to upgrade the thank-you and order status pages arrived on August 26, 2026. Stores that had not upgraded by hand were upgraded automatically, and anything the old code or scripts did may simply be gone. [The tracking that broke with the upgrade is the same kind of loss as a slow product page: fixing slow product-page load on Shopify is the first step, and re-implementing the tracking through the Web Pixels API is the second](https://deftmerch.com/blog/2026-11-10-product-page-lcp-shopify-fix.md).

## What each plan can change now

On every plan from Basic up, the merchant gets the checkout editor for the logo, colours, fonts, and backgrounds, and apps that customize the thank-you and order status pages. Those two are the baseline, and they are the same on Basic and on Plus.

On Plus, the merchant gets the valuable part: checkout UI extensions on the information, shipping, and payment steps, which let an app add its own interface to the checkout itself, and the Checkout Branding API for deeper styling. Merchants can add up to three checkout UI extensions to the same block target, and each extension's compiled bundle is capped at 64 KB.

Public App Store apps that contain Functions work on any plan. Custom apps that contain Functions need Shopify Plus. Market-specific checkout customization is available on Advanced as well as Plus. The plan decides the work, and the work is different on every plan.

## What to rebuild, and in what order

First, the tracking. Tracking from GTM, Meta, and Klaviyo has to be re-implemented through the Web Pixels API and customer events, or the conversions those scripts reported stop arriving. The tracking is the revenue data, and it is the first thing to rebuild, because the store that cannot see its conversions cannot judge its checkout.

Second, the discount and delivery logic. Shopify Scripts are gone, so the logic has to be rebuilt as Shopify Functions, and the Functions have to be tested against the same cases the Scripts handled, because a discount rule that worked for two years has edge cases nobody remembers.

Third, the interface. The checkout UI extensions replace the custom interface the old checkout.liquid file carried, and the extensions have to be built for the slots Shopify allows, in the styles Shopify allows. The trade-off is less freedom, and the gain is that Shopify updates the checkout around the extensions instead of breaking them. [The same discipline applies to the product page: when too many variants kill the sale, the fix is the structure, not more copy, and the checkout fix is the same, the structure first, the styling second](https://deftmerch.com/blog/2026-11-10-variant-sprawl-too-many-options.md).

## Frequently asked questions

### Is checkout.liquid still available on Shopify Plus?

No. It stopped working on the information, shipping, and payment pages on August 13, 2024, and was sunset on the thank-you and order status pages on August 28, 2025. Customization now lives in apps and extensions.

### What is checkout extensibility?

It is the set of tools that replaced hand-editing the checkout code: the checkout editor, checkout UI extensions, Shopify Functions, and pixels. The customization lives in apps and extensions that Shopify loads into defined slots, and Shopify updates the checkout around them.

### Do I need Shopify Plus to customize checkout?

Not for the basics. Every plan from Basic up gets the checkout editor and apps on the thank-you and order status pages. Plus is needed for UI extensions on the information, shipping, and payment steps, for the Checkout Branding API, and for custom apps containing Functions.

### What replaced Shopify Scripts?

Shopify Functions. Scripts stopped executing on June 30, 2026, and discount, delivery, and payment logic now runs on Functions. Public App Store apps with Functions work on any plan; custom apps with Functions need Plus.