Checkout Extensibility vs Checkout.liquid: What Replaces It and What Each Plan Gets

Checkout.liquid is dead, and if your store still has customizations that depend on it, they are already gone or about to go. The file was always Plus-only, and Shopify made it unsupported for the Information, Shipping, and Payment steps, then sunset it on the Thank you and Order status pages on August 28, 2025 for Plus stores and August 26, 2026 for everyone else. Stores that missed those dates were auto-upgraded, and the old code stopped running silently. The replacement is checkout extensibility: customization now lives in apps and extensions that run in a Shopify-hosted sandbox, and Shopify updates the checkout around them. Tracking moves to the Web Pixels API and customer events. Logic moves to Shopify Functions. The checkout itself belongs to Shopify now, and that is the point.

The dates, and what happened on them

Four legacy mechanisms retired on different dates, and the dates matter because the failure is silent. Checkout.liquid, the Plus-only layout file, became unsupported on the Information, Shipping, and Payment steps with no official day attached, and was sunset on the Thank you and Order status pages on August 28, 2025 for Plus stores and August 26, 2026 for everyone else. Plus stores went through the upgrade on August 28, 2025, and automatic upgrades began in January 2026, with customizations lost. Non-Plus stores had until August 26, 2026; pages not upgraded by hand were upgraded automatically, and the revert route was open before that date rather than after it. Shopify Scripts stopped executing on June 30, 2026. Script tags were blocked on the Order status page on August 28, 2025 for Plus and August 26, 2026 for other plans, the Admin API stops accepting new and updated ScriptTags on October 1, 2026, and script tags stop running on storefronts on March 1, 2027. Anything still pasted in those fields stops firing on those dates, silently, which is exactly the analytics-data-went-missing-with-no-warning experience merchants describe.

What extensibility actually is

Checkout extensibility flips the old model. Under checkout.liquid, the merchant edited Shopify's checkout code directly, and every change Shopify shipped was a possible break in the template. Under extensibility, the merchant never edits checkout code: the checkout itself belongs to Shopify, and everything custom is an app extension that Shopify loads into well-defined slots. Extensions use versioned APIs, the current version in Shopify's docs is 2026-10, and Shopify updates the checkout around them. That is why the model is called upgrade-safe: adopting a new feature, like one-page checkout, does not require rework, because the customizations live in the extensions, not in the checkout code. The model applies to every plan, but not every slot is open to every plan, and that is where merchants get confused.

What each plan can actually use

Checkout UI extensions, custom blocks inside the checkout, are available on Plus for the Information, Shipping, and Payment steps. Extensions for the Thank you and Order status pages are available on all plans except Shopify Starter. The branding API, colors, corner radius, and similar, is Plus only. Shopify Functions, custom logic for discounts, payment options, delivery options, and checkout validation, are available on all plans except Starter. Web pixel extensions for tracking are available on all plans except Starter. The practical reading is that a non-Plus store can customize the Thank you and Order status pages, can add custom discount and validation logic, and can run tracking, but cannot put custom blocks inside the Information, Shipping, and Payment steps, and cannot rebrand the checkout through the API. A Plus store can do all of it, and the price difference is the price of those two slots.

What to rebuild first

Start with the checkout upgrade report in the Shopify admin, which shows what is still holding up the upgrade. Then rebuild in the order that costs money when it is missing. Tracking first, because every day without it is a day of unmeasured ad spend: re-implement GTM, Meta, and Klaviyo through the Web Pixels API and customer events, and check the Google and YouTube channel app for the conversion sources it explicitly covers. Then the Thank you and Order status page extensions, because those are available on every plan and they are where post-purchase upsells and surveys live. Then the Functions, for the discount and validation logic that used to live in Shopify Scripts. Plan the checkout, thank-you page, and order status page upgrades together, so you do not have to maintain two technology stacks side by side. And stop reading old blog posts that describe checkout.liquid as current: the file is gone, the scripts are gone, and the extensions are the only supported path.

Frequently asked questions

Does checkout.liquid still work on my store?

For the Information, Shipping, and Payment steps, no: it is no longer supported. For the Thank you and Order status pages, it was sunset on August 28, 2025 for Plus stores and August 26, 2026 for other plans. Stores that had not upgraded by those dates were auto-upgraded, and the old customizations stopped running. If your checkout still looks customized, check whether the customization is an extension or a leftover that stopped firing.

What is checkout extensibility, in plain terms?

It is the model in which a merchant never edits checkout code. The checkout itself belongs to Shopify, and everything custom is an app extension that Shopify loads into well-defined slots. Extensions use versioned APIs, the current version is 2026-10, and Shopify updates the checkout around them, so an upgrade does not break your customizations the way it did under checkout.liquid.

What can I customize without Shopify Plus?

Thank you and Order status page extensions work on every plan except Starter. Shopify Functions, for custom discount, payment, delivery, and validation logic, are available on all plans except Starter. Web pixel extensions for tracking are available on all plans except Starter. What needs Plus is checkout UI extensions on the Information, Shipping, and Payment steps, and checkout branding through the GraphQL Admin API.

What happened to my Google Analytics and Meta tracking?

It stopped firing when the old scripts were disabled. Tracking from GTM, Meta, and Klaviyo has to be re-implemented through the Web Pixels API and customer events, in Settings, then Customer events. The Google and YouTube channel app covers the conversion sources it explicitly lists in its own settings. If your analytics went missing with no warning after an upgrade, the old additional scripts are the cause.