# Shopify Checkout Extensibility: The App Blocks That Replaced checkout.liquid

Source: https://checkoutoptimizelab.com/2026-11-15-shopify-checkout-extensibility-app-blocks.html

*checkout.liquid is gone. The last deadline passed on August 26, 2026, when the thank you and order status pages were retired for non-Plus stores, and every store is past every deadline now. The stores still looking for their checkout customizations in a file they used to edit are looking in the wrong place. The replacement is four building blocks, and the one most stores need is the simplest: the app block, placed in the checkout editor, doing the job the liquid code used to do.*

## Four blocks, and most stores need one

Checkout extensibility is four tools. Checkout UI extensions are the visible blocks: a delivery note, a survey, an upsell, a loyalty message, placed at fixed spots in the checkout editor. Shopify Functions are the logic: discounts, delivery rules, payment rules, running as code the merchant never sees. The Checkout Branding API is the styling: colours, fonts, and the logo, changed through the editor. Web Pixels are the tracking: app pixels and custom pixels in Customer events, running in a sandbox on checkout and the thank you page. Most stores need the first one. They had a visible customization in checkout.liquid, a message or an upsell or a custom field, and the replacement is an app that offers it as a block. Install the app, place the block in the editor, and the customization is back, without a line of code.

The timeline is worth knowing, because it explains why some stores lost customizations on different dates. The information, shipping, and payment steps were retired for all stores on August 13, 2024. The thank you and order status pages went for Plus stores on August 28, 2025, and for every other store on August 26, 2026. Stores that had not upgraded were upgraded automatically, and the code in the Additional scripts box stopped running. Anything that sat on the thank you page through additional scripts, a conversion tag, an affiliate pixel, a discount code for the next order, is gone unless it was moved. Tracking now belongs in web pixels. Visible elements belong in app blocks. Code in the theme never runs in checkout or on the thank you page, so a tag in theme.liquid is not a backup.

## Plus still decides where blocks can go

The split that matters most is the plan split. On every plan from Basic up, you can brand the checkout, edit the form fields, and add eligible app blocks to the thank you and order status pages. Blocks inside the information, shipping, and payment steps are Shopify Plus only, and so are the Checkout Branding API and custom apps built with Shopify Functions. Shopify's own free Checkout Blocks app is the starting point for most stores: its content blocks work on the thank you and order status pages for everyone, and its step blocks, custom discounts, and payment and delivery rules need Plus. [The deadline post covered what broke on August 26](https://checkoutoptimizelab.com/2026-11-09-checkout-liquid-gone-what-breaks-after-deadline.md), and the blocks post is the other half of that story: what replaced it, and where the replacement is allowed to live. [The Branding API post covers the styling half](https://checkoutoptimizelab.com/2026-11-09-checkout-branding-api-without-plus.md), which is the part that stays Plus-only even when the content blocks do not.

## Start with the thank you page

If you have not migrated yet, start with the thank you page, because it is the page every plan can customize and the page where the missing upsell or survey is most visible. Open Settings, then Checkout, then Customize, set the page picker to the thank you page, and add the app block. If the app you need is not in the list, it has not been rebuilt for extensibility, and you need an alternative, not a workaround. There is no workaround. Script tags stop running on storefront pages too from March 1, 2027, and since October 1, 2026 apps cannot create or update them. The migration is not a project to schedule. It is a page to open, and the blocks are already there.

The honest check is the checkout itself. Place the test order, walk the steps, and look at the thank you page. If the upsell is there, the migration worked. If it is not, the app has not been rebuilt, and the store is running a checkout with a hole in it that no amount of theme editing will fill.

## Frequently asked questions

### Is checkout.liquid really gone for all stores?

Yes. The information, shipping, and payment steps were retired on August 13, 2024, the thank you and order status pages went for Plus stores on August 28, 2025, and for all other stores on August 26, 2026. Stores that had not upgraded were upgraded automatically, and remaining checkout.liquid customizations were removed.

### What replaces checkout.liquid?

Four building blocks: checkout UI extensions for visible blocks, Shopify Functions for discounts and delivery and payment rules, the Checkout Branding API for styling, and Web Pixels for tracking. Most stores need the UI extensions, which are app blocks placed in the checkout editor.

### Can I add app blocks inside the checkout steps without Plus?

No. Blocks on the thank you and order status pages work on every plan from Basic up. Blocks inside the information, shipping, and payment steps, and the Checkout Branding API, are Shopify Plus only. Shopify's free Checkout Blocks app follows the same split.

### Where did my thank you page tracking go?

It moved to Customer events. Tracking that used to live in the Additional scripts box now runs as app pixels or custom pixels in Settings, Customer events, loaded in a sandbox on checkout and the thank you page. Code in the theme never runs in checkout, so a theme tag is not a replacement.