Checkout Extensibility in 2026: What Non-Developers Need to Know

checkout.liquid and Shopify Scripts, the two tools Shopify Plus merchants used for years to change how checkout looks and works, are gone. checkout.liquid stopped working for the Information, Shipping and Payment pages on 13 August 2024, and for the Thank you and Order status pages on Shopify Plus on 28 August 2025. Shopify Scripts could no longer be edited or published from 15 April 2026 and stopped running on 30 June 2026. Today, every checkout customization on Shopify goes through Checkout Extensibility: the checkout editor, apps with checkout UI extensions, Shopify Functions, the Checkout Branding API and pixels.

This guide is for merchants and e-commerce managers, not developers. It explains what replaced each old customization, which parts you can handle yourself in the admin, which ones need a developer, and what to check if your checkout was upgraded automatically.

Where Things Stand in 2026

Sources: Shopify changelog on checkout.liquid, Shopify Help Center: Thank you and Order status upgrade, Shopify changelog on Scripts.

All the deadlines have passed, so the question is no longer "when do we upgrade", but "does our checkout still do everything it did before". If your store was upgraded automatically, some customizations may simply have disappeared: a delivery message, a gift note field, a conversion tag on the Thank you page, a discount rule written in Scripts.

If you want someone to review your checkout and rebuild what's missing, our Shopify Plus development team does this regularly.

What Was checkout.liquid and Why Did Shopify Retire It?

checkout.liquid was a theme file written in Liquid that rendered the checkout page. On plans below Shopify Plus it couldn't be edited at all. Shopify Plus merchants could unlock it and change almost anything, usually with a developer's help, but every change sat directly in the most critical part of the store. Custom code could break whenever Shopify changed checkout, and stores with heavy modifications couldn't simply take new checkout features, such as the one-page checkout that became the default in October 2023.

Checkout Extensibility replaces free-form code with defined places where apps and settings can plug in. You lose some freedom, but customizations survive Shopify's updates, are easier to maintain and many of them can be added without a developer.

What Is Checkout Extensibility?

Checkout Extensibility is an umbrella term for the tools that now customize checkout. Some of them work from the admin without code, some need a developer, and some are reserved for Shopify Plus. In short:

• On all paid plans (Basic and higher): standard branding in the checkout editor (logo, colors, fonts), apps on the Thank you and Order status pages, pixels in Customer events and public apps that use Shopify Functions.
• Only on Shopify Plus: apps and checkout UI extensions on the Information, Shipping and Payment steps, the Checkout Branding API and custom apps with Shopify Functions.

Sources: Shopify Help Center: customizing checkout, shopify.dev: Shopify Functions.

Let's start with the changes you can make on your own.

Code-Free Tools in the Shopify Admin

Checkout and accounts editor

The checkout and accounts editor is a visual editor for checkout, the Thank you and Order status pages and customer account pages, separate from the theme editor. To open it, go to Settings > Checkout, and in the Configurations section click Edit on the configuration you want to change. You can customize both the active and draft configurations, so changes can be prepared and checked before customers see them (Shopify Help Center: checkout editor).

💡 Find out more about the drag-and-drop checkout editor (Shopify video from the launch, the interface has changed slightly since)

Checkout apps from the Shopify App Store

From the editor you can install apps that add blocks to checkout and then place their blocks where you need them, for example an upsell in the order summary. On Basic, Grow and Advanced these apps work on the Thank you and Order status pages. Apps on the Information, Shipping and Payment steps require Shopify Plus.

App developers keep adding ideas for improving metrics such as conversion rate, AOV and LTV. When no app fits, a custom Shopify app can add the block you need.

Pixels in Customer events

Pixels are pieces of JavaScript that track customer behavior across your online store, including checkout, mostly for marketing and analytics. You manage them in the Customer events section of the admin. There are two kinds (Shopify Help Center: pixels):

• App pixels, installed by marketing and analytics apps (Shopify recommends them where possible, because they are more secure and update automatically). You can browse pixel apps in the App Store.
• Custom pixels, added manually by a developer when no app covers your case.

This matters because the old way of adding tracking, pasting code into Additional scripts on the Thank you page, no longer works: since 28 August 2025 that section is view-only. Custom pixels load in a sandbox, and Shopify notes that not all pixel functionality works there (Shopify Help Center: custom pixels), so some older tags need adjusting. In the Eveline Cosmetics project we built a custom Google Tag Manager configuration with a dedicated dataLayer to work around Customer events restrictions (Eveline Cosmetics case study). If your conversion numbers dropped after the upgrade, check your pixels first.

Developer Tools in Checkout Extensibility

The tools below need a developer, or an app built by one.

Checkout Branding API (Shopify Plus)

The checkout editor covers the basics: logo, colors and fonts. When you need more, such as the look of form fields, typography, corner radius or section backgrounds, a developer can use the Checkout Branding API. It is available only on Shopify Plus.

The styles apply across checkout, the checkout queue, checkout UI extensions and customer account pages (shopify.dev: checkout styling), so installed checkout apps automatically match your brand and you manage the design in one place.

Checkout UI extensions

Checkout UI extensions are the app blocks you place in the checkout editor. Developers build them with Shopify's Polaris web components, and an extension can query the Storefront API, for example to read customer or product data for its logic (shopify.dev: checkout UI extensions). Extensions on the Information, Shipping and Payment steps are available only on Shopify Plus. Extensions on the Thank you and Order status pages work on other plans too.

Typical uses:

• an upsell or cross-sell section
• a gift message or other extra field
• a checkbox such as "pack as a gift" or "send to someone else"
• delivery messages, alerts and information about the order
• choosing a pickup point
• loyalty: recognizing the customer and showing their points

Examples from our projects (all from published case studies):

• The Odder Side: the old store needed numerous checkout.liquid modifications. After the migration to Shopify Plus, checkout was extended within Checkout Extensibility with pickup points (such as DHL or local pickup) and promotions from discount codes to automatic gifts above a set cart value (case study).
• Eveline Cosmetics: gift with purchase logic based on three spending thresholds and dedicated upsell modules built directly into checkout, so customers don't need extra clicks to get gifts and premium packaging (case study).
• Naturopathica: a B2B store on Shopify Plus where wholesale customers save products for later orders in a wishlist built with customer account extensions (case study). More on B2B checkout in our guide to B2B on Shopify.

Web pixel app extensions

A web pixel app extension is the developer's way to ship a pixel inside an app, to track customer events in a controlled, sandboxed way. Before building your own pixel, check whether a tested app already does the job. Every additional script still has a cost, so keep only the tracking you actually use.

Shopify Functions (the replacement for Scripts)

Shopify Functions let developers change Shopify's backend logic: how discounts are calculated, which payment and delivery options are shown, whether a cart can go through checkout. They replaced Shopify Scripts, which stopped running on 30 June 2026. Examples from Shopify's documentation (shopify.dev: Shopify Functions):

• new discount types
• hiding a payment method, for example for customers with a specific tag
• renaming a delivery option
• product bundles sold as one unit
• validating the cart, for example blocking checkout above a quantity limit
• order routing and fulfillment rules, local pickup and pickup points

Stores on any plan can use public App Store apps that contain functions. Custom apps with Function APIs, the usual way to rebuild bespoke Scripts logic, are available only on Shopify Plus. Many discount combinations no longer need code at all, because Shopify lets you combine discounts natively (Shopify Help Center: discount combinations).

Post-purchase extensions

Post-purchase extensions show a page after payment but before the Thank you page. They are still in beta: developers can use them freely in development stores, but a live store needs to request access (shopify.dev: product offers). In practice merchants use them through apps. Typical uses:

• a one-click upsell added to the order
• a short survey, while the customer is still engaged
• a discount code for the next order
• signing up for a loyalty program or creating an account

How to Audit and Rebuild Your Checkout Today

Most stores have already been moved to the new checkout, either by their own project or automatically. The work now is making sure nothing important was lost.

1. Make a list of what checkout used to do. Old checkout.liquid code, Scripts, additional scripts on the Thank you page, tracking tags. If you upgraded the Thank you and Order status pages from the admin, Shopify generated a personalized upgrade guide with a customizations report and your additional scripts grouped by purpose. You find it in Settings > Checkout (Shopify Help Center).
2. Decide what is still worth having. Not every old customization adds business value. Drop the ones that don't.
3. Map the rest to the new tools. The checkout editor and an existing app first, then a custom extension or function. Some things that were possible in checkout.liquid have no equivalent, so check feasibility before you promise them to the business.
4. Rebuild Scripts as Functions. Discounts, shipping and payment rules from Scripts stopped working on 30 June 2026. If a promotion "suddenly" stopped applying, this is usually why.
5. Move tracking to pixels. Check that purchase events reach your analytics and ad platforms, and compare conversion data before and after the change.
6. Build on a draft configuration and test. Place test orders for every payment and delivery method and each market. After going live, watch conversion rate and AOV to make sure nothing is getting in customers' way.

If checkout customization is a deciding factor in choosing a plan, compare what's Plus-only in our articles on Shopify Plus vs Advanced and Shopify pricing in 2026. Moving from Magento, where checkout can be changed in code without limits? Our Shopify Plus vs Magento comparison explains the trade-offs.

Checkout is the most sensitive part of any online store, and changes there can be stressful. If you'd like us to review your checkout or rebuild missing customizations, contact us.