26 July 2026 · Checkout
Shopify checkout UI extensions: a no-code guide
Shopify checkout UI extensions are pre-built or custom interface components that merchants can add to Shopify checkout, thank-you, and order-status pages. They are the building blocks of Shopify's modern checkout customization strategy.
Short answer: UI extensions let you add custom components to checkout without editing theme code. You can use pre-built extensions from apps or build your own if you have development resources. For subscriptions, extensions improve the experience but the billing engine should still be separate, like Checkivo on Stripe. Related: Shopify checkout blocks app and Shopify Plus custom checkout.
What checkout UI extensions are
Checkout UI extensions are components that render inside Shopify's secure checkout environment. They can display information, collect input, offer upsells, or show trust signals. Because they run inside Shopify's checkout, they are safer and more stable than the old checkout.liquid approach.
Extensions are different from fully custom checkout code. You do not write HTML or CSS that replaces Shopify checkout. Instead, you build or install components that Shopify places at specific extension points.
For merchants, this means you can customize checkout without worrying about breaking payment processing or compliance.
Types of UI extensions
Shopify supports several types of checkout UI extensions:
Block extensions. Add content blocks at specific points in checkout, such as banners, fields, or upsells.
Field extensions. Capture custom data from the customer and store it with the order.
Delivery customization extensions. Adjust delivery options based on cart or customer data.
Payment customization extensions. Control which payment options are shown.
Order status and thank-you extensions. Add content after purchase.
Each type has a specific purpose and a specific place in the checkout flow. Pick the type that matches your goal rather than forcing a block to do something it was not designed for.
No-code setup with apps
The easiest way to use UI extensions is through apps in the Shopify App Store. These apps provide pre-built extensions that you configure and place in the checkout editor.
Steps:
Install an app that offers checkout extensions.
Open Settings → Checkout and click Customize checkout.
Drag the extension to the desired checkout section.
Configure the extension settings.
Preview and save.
This is the same workflow as checkout blocks. Many apps use the terms interchangeably, though technically extensions are the underlying framework and blocks are the merchant-facing components.
Custom extensions
If you need something unique, you can build a custom checkout UI extension. This requires a developer familiar with Shopify's extension framework, React, and the Shopify CLI.
Custom extensions are useful when:
No app offers the exact component you need.
You need deep integration with your own backend.
You want full control over the component behavior and data.
The trade-off is maintenance. Shopify updates the extension framework regularly, and custom extensions must be kept compatible.
Where extensions can appear
Extensions can be placed at specific points in the checkout journey. Common targets include:
Checkout contact information step.
Shipping step.
Payment step.
Order summary sidebar.
Thank-you page.
Order status page.
Not every extension type works at every target. The app or developer documentation will specify where an extension can be placed.
Limits and rules
Checkout UI extensions run in a sandboxed environment. They cannot:
Modify the order total directly.
Access external scripts or iframes.
Skip Shopify's required checkout steps.
Store sensitive data outside Shopify's approved patterns.
These limits protect checkout security and compliance. They also mean extensions are for experience and data capture, not for core billing logic.
UI extensions for subscriptions
Subscriptions benefit from UI extensions in several ways:
Plan selection blocks at checkout.
Transparency banners explaining billing cadence.
Custom fields for delivery preferences or consent.
Post-purchase upsells for add-on subscriptions.
Again, the extension handles the UI. The actual recurring billing, renewals, and dunning should be handled by a subscription engine. Checkivo provides that engine on Stripe, so the extensions can focus on the customer experience.
Common extension mistakes
Merchants often install too many extensions. Each extension adds load time and complexity. A checkout with five extensions from three different apps can feel slow and confusing.
Another mistake is choosing an extension that does not match the intended target. Not every extension can be placed at every checkout step. Read the app documentation before buying.
Custom extensions sometimes break after Shopify updates. If you build your own, budget for ongoing maintenance and testing.
Extension implementation checklist
Before launching an extension:
Define the customer problem it solves.
Confirm the extension works on mobile and desktop.
Measure checkout load time before and after.
Verify data flows to the right place in your systems.
Test with real transactions and payment methods.
Set a review date to decide if it stays or goes.
Key takeaways
Checkout UI extensions are powerful but should be used intentionally. Start with one or two high-impact extensions. For subscriptions, use extensions for the experience and Checkivo for the billing engine.
Examples of useful UI extensions
Not every merchant needs custom extensions. Here are examples that deliver clear value:
Order protection upsell. A post-purchase extension offers shipping insurance. It is relevant to the customer and increases AOV without interrupting the core purchase.
Delivery date picker. A field extension lets customers choose a preferred delivery window. This reduces missed deliveries and support tickets.
Subscription plan selector. A block at checkout lets customers choose monthly or annual billing. It must be paired with a reliable subscription engine, but the extension handles the UI.
Each example is tied to a specific outcome. Avoid extensions that are purely decorative or that add friction without a clear benefit.
Maintaining UI extensions
UI extensions require maintenance. Shopify updates the checkout framework, apps release new versions, and customer behavior changes. Schedule a quarterly review of your extensions: remove unused ones, update outdated ones, and measure the performance of the rest.
Also keep an eye on checkout load time. An extension that adds half a second to mobile load can hurt conversion more than it helps.
Security and compliance
Checkout UI extensions run in a tightly controlled environment. Shopify reviews apps that use extensions and enforces rules about data handling. This protects customer payment information and keeps the checkout compliant with PCI requirements.
When evaluating a checkout extension app, check its privacy policy and data handling. Extensions that capture customer data should store it securely and only collect what is necessary. Avoid extensions that ask for excessive permissions or that load scripts from untrusted sources.
Performance impact
Every extension adds JavaScript and render time to checkout. On mobile, this matters a lot. A single slow extension can erase the conversion benefit of all other checkout optimizations. Measure mobile load time with tools like Shopify's Web Performance dashboard or Chrome DevTools. If an extension adds more than a few hundred milliseconds, question whether it is worth keeping.
Frequently asked questions
What are Shopify checkout UI extensions?
They are components that add custom UI to Shopify checkout, thank-you, and order-status pages without editing theme code.
Do I need to code to use UI extensions?
No. Many apps offer pre-built extensions you can configure through the checkout editor.
Can I build my own checkout extension?
Yes, if you have a developer. Shopify provides a framework and CLI for building custom extensions.
What is the difference between blocks and extensions?
Extensions are the underlying technical framework. Blocks are the merchant-facing components you drag into the checkout editor.
Where can UI extensions appear?
At specific points in checkout, thank-you, and order-status pages, depending on the extension type.
Can UI extensions change the order total?
No. They cannot modify pricing directly. Use Shopify Functions or discount logic for that.
Do UI extensions work on mobile?
Yes. They are designed to work within Shopify's responsive checkout.
Can UI extensions handle subscriptions?
They can handle the UI and data capture, but recurring billing needs a subscription engine.
How does Checkivo work with UI extensions?
Checkivo manages the subscription backend, while UI extensions can provide plan selection, transparency, and account portal links.
Do UI extensions slow down checkout?
They can if overused. Keep the number of extensions low and measure load time.
Can I use UI extensions for B2B checkout?
Yes, on Shopify Plus with B2B features, you can customize the checkout experience for company accounts.
Do UI extensions work with headless Shopify?
Headless storefronts use a different checkout approach. Standard checkout UI extensions are for Shopify's native checkout.
Can I use a UI extension for age verification?
Yes, there are apps that provide age verification blocks at checkout.
Are UI extensions available on Shopify POS?
POS has its own extension system. UI extensions for online checkout are separate.