Building Shopify Checkout Extensions: Customize and Enhance the Shopify Checkout Experience

Introduction

The Shopify checkout experience is one of the fastest and most optimised in eCommerce—but what if your business requires more than the default? For high-growth brands using Shopify Plus, Checkout Extensions offer a powerful way to enhance and personalise the final step of the buyer journey—without compromising performance or PCI compliance.

Whether you want to add custom messages, create upsell opportunities, or collect additional customer data, Shopify Checkout Extensions give you the tools to build tailored, functional experiences directly within Shopify’s secure checkout.

In this guide, you’ll learn what Checkout Extensions are, how to build them using Shopify’s modern development stack, and how to leverage them to increase conversions, improve customer experience, and streamline backend workflows.

1. What Are Shopify Checkout Extensions?

A New Era of Checkout Customisation

Shopify Checkout Extensions are part of Shopify’s Checkout Extensibility framework—a modern alternative to the legacy checkout.liquid customisation method.

Benefits of Checkout Extensions:

• Secure and fully PCI-compliant
• Built on React and Shopify UI components
• Compatible with Shopify’s one-page checkout
• Lightweight and fast-loading
• Easily manageable via the Checkout Editor

Note: Checkout Extensions are available exclusively to Shopify Plus stores.

2. Prerequisites Before You Begin

Before building a checkout extension, ensure you have the right tools and environment in place.

You’ll need:

• A Shopify Partner account
• A Shopify Plus development store with checkout extensibility enabled
• Shopify CLI v3+ installed
• Node.js and npm
• Basic React/JavaScript knowledge

Shopify CLI Installation:

bashCopyEditnpm install -g @shopify/cli @shopify/app

Once installed, you’re ready to create your first extension.

3. Creating a Checkout Extension with Shopify CLI

The Shopify CLI makes it easy to scaffold, test, and deploy extensions.

Step-by-step:

1. Create a new extension:

bashCopyEditshopify extension create

2. Choose “Checkout UI Extension” when prompted
3. Navigate to your extension directory:

bashCopyEditcd extensions/your-extension-name

4. Start the local server:

bashCopyEditshopify extension serve

5. Open your dev store to preview changes in real time

Pro Tip: Use shopify extension push to deploy updates once testing is complete.

4. Extension Points: Where You Can Inject Custom Code

Shopify provides predefined extension points where you can insert UI elements or logic during the checkout flow.

Popular extension points:

• Checkout::DeliveryMethods::RenderAfter
• Checkout::ShippingMethods::RenderAfter
• Checkout::LineItem::RenderAfter
• Checkout::Payment::RenderAfter
• Checkout::Actions::RenderBefore

Each point gives access to specific checkout context data like customer info, shipping address, and cart line items.

5. Building a Custom Field (Example)

Let’s create a simple text input to collect delivery instructions using the @shopify/checkout-ui-extensions-react library.

Sample Code:

jsxCopyEditimport {
  reactExtension,
  TextField,
  useExtensionApi,
} from '@shopify/checkout-ui-extensions-react';

export default reactExtension('Checkout::DeliveryMethods::RenderAfter', () => {
  const {checkout} = useExtensionApi();

  return (
    <TextField
      label="Delivery Instructions"
      multiline
      onChange={(value) => {
        console.log('Customer input:', value);
      }}
    />
  );
});

This code adds a custom input field during the shipping selection step and logs the customer input for future integration.

6. Best Practices for Checkout Extension Development

To ensure smooth performance and user experience:

• Keep UI minimal and relevant
• Follow Shopify’s design system for consistent styling
• Use extension points wisely—don’t clutter the checkout
• Minimise API calls for faster load times
• Validate all customer inputs for safety and clarity

Accessibility Tip: Ensure your extensions are keyboard-navigable and screen-reader friendly.

7. Deploying and Publishing Your Extension

Once your extension is built and tested:

Deploy with:

bashCopyEditshopify extension push

Enable in your store via:

• Shopify Admin → Settings → Checkout
• Launch the Checkout Editor
• Add your extension block where needed
• Configure visibility rules or conditional logic

Changes take effect immediately once published.

8. Advanced Use Cases for Checkout Extensions

Checkout Extensions aren’t just cosmetic—they can drive real value.

Examples:

• Gift message field: Personalise orders with optional gift notes
• Loyalty point summary: Display remaining points or discounts applied
• Legal checkbox: Require customers to accept terms before completing purchase
• Cross-sell widget: Suggest complementary products based on cart contents
• Custom delivery instructions: Allow additional info for logistics

Pair extensions with Shopify Functions to implement dynamic shipping rules, custom discounts, or payment logic.

9. Checkout Extensions vs. checkout.liquid: Key Differences

Shopify has announced the deprecation of checkout.liquid by August 2024, making Checkout Extensions the future-proof path forward.

10. Monitoring and Maintaining Your Extension

Even after publishing, you should monitor and refine your checkout extension based on customer behaviour and business needs.

Post-launch tips:

• Collect feedback via heatmaps or surveys
• Track abandonment rates and form completion
• Update styling and messaging seasonally
• Monitor performance via Lighthouse or Shopify analytics

Pro Tip: Test extensions regularly when new themes or Shopify updates roll out.

Conclusion

Shopify Checkout Extensions give merchants and developers the ability to create high-performance, secure, and deeply customised checkout experiences—without sacrificing speed or future compatibility. By leveraging these tools strategically, you can boost conversions, collect meaningful data, and elevate the entire customer journey.

At [Your Agency or Brand Name], we help Shopify Plus merchants unlock the full potential of Checkout Extensions through custom development and CRO-optimised UX.

Ready to enhance your Shopify checkout? Let’s build something powerful together.