Shopify Checkout Extensibility Development

It is Shopify's supported way to customise checkout, now called Shopify Extensions in Checkout. Instead of editing checkout code, you add checkout UI extensions for content and fields, Shopify Functions for discount, delivery and payment logic, branding settings for the look, and web pixels for tracking. These survive Shopify's checkout updates.

No. checkout.liquid is unsupported for the information, shipping and payment steps. On the Thank you and Order status pages, checkout.liquid and additional scripts were sunset on 28 August 2025. Script tags on those pages were sunset for Plus stores on 28 August 2025 and for other stores on 26 August 2026.

For some changes. Checkout UI extensions on the information, shipping and payment steps are available only to Shopify Plus stores, and custom apps containing Shopify Functions run only on Plus. On other plans, stores customise mainly through Thank you and Order status page extensions, checkout editor branding and web pixels. We check your plan before designing anything.

They add content and inputs at defined points in checkout: banners, custom fields, delivery instructions, gift messages, product offers, surveys on the Thank you page and review requests on the Order status page. They run in an isolated environment and only see the checkout data Shopify exposes to them, which keeps the core checkout under Shopify's control.

Functions run your own logic inside Shopify's checkout: custom discount rules, hiding, renaming or reordering delivery and payment options, and validation such as blocking an order that breaks a business rule. They replace logic that older stores ran in checkout scripts.

Only if it is moved deliberately. Tracking code in checkout.liquid, additional scripts and script tags no longer runs on the sunset pages, so purchase events must come from web pixels or a server-side integration. We list every tag in the inventory and confirm each one fires after release.

Shopify Functions. Shopify Scripts were sunset on 28 August 2025, and custom discount, shipping and payment logic now runs as Functions inside the checkout. Custom apps that contain Functions run only on Shopify Plus, while App Store apps with Functions work on any plan.

The Shopify admin includes a report of your current checkout customisations, with guidance on how each maps to Shopify Extensions in Checkout. We use it as the starting point and check it against the live checkout, because tags added outside Shopify settings can be missed.

Yes. Checkout UI extensions can be localised, so text and formatting follow the buyer's language and currency. For stores selling in several markets we build translations into the extension from the start rather than adding them after launch.

As a fixed scope, quoted in writing after the inventory. The quote depends on how many customisations need custom extensions or Functions rather than settings and apps. Some stores only need a short mapping exercise and configuration; others need a custom checkout app.