Checkout UI extensions

Checkout UI extensions let app developers build custom functionality that merchants can install at defined points in the checkout flow, including product information, shipping, payment, order summary, and Shop Pay. > Shopify Plus: >Checkout UI extensions for the information, shipping and payment step are available only to stores on a [Shopify Plus](https://www.shopify.com/plus) plan.

Scaffolding an extension

Scaffolding an extension

Use Shopify CLI to [generate a new extension](/apps/tools/cli/commands#generate-extension) in the directory of your app.

Scaffolding

npm init @shopify/app@latest
cd your-app
npm run shopify app generate extension

yarn create @shopify/app
cd your-app
yarn shopify app generate extension

pnpm create @shopify/app
cd your-app
pnpm shopify app generate extension

Extension Targets

Extension Targets

Extension targets provide locations where merchants can insert custom content. Static extension targets are tied to core checkout features like contact information, shipping methods, and order summary line items. Block extension targets can be displayed at any point in the checkout process and will always render regardless of which checkout features are available. An example is a field to capture order notes from the customer. Extension UIs are rendered using [remote UI](https://github.com/Shopify/remote-dom/tree/remote-ui), a fast and secure environment for custom [(non-DOM)](#security) UIs.

Extension targets

import {
  reactExtension,
  Banner,
} from '@shopify/ui-extensions-react/checkout';

export default reactExtension(
  'purchase.checkout.block.render',
  () => <Extension />,
);

function Extension() {
  return <Banner>Your extension</Banner>;
}

import {
  extension,
  Banner,
} from '@shopify/ui-extensions/checkout';

export default extension(
  'purchase.checkout.block.render',
  (root, api) => {
    const banner = root.createComponent(
      Banner,
      {},
      'Your extension',
    );
    root.appendChild(banner);
  },
);

Configuration file

Configuration file

When you create a checkout UI extension, the `shopify.extension.toml` file is automatically generated in your checkout UI extension directory. It contains the extension's configuration, which includes the extension name, extension targets, metafields, capabilities, and settings definition.

shopify.extension.toml

api_version = "2023-07"

[[extensions]]
type = "ui_extension"
name = "My checkout extension"
handle = "checkout-ui"

  [[extensions.targeting]]
  target = "purchase.checkout.block.render"
  module = "./Checkout.jsx"

Extension APIs

Extension APIs

APIs enable checkout UI extensions to get information about the checkout or related objects and to perform actions. For example, you can use the APIs to retrieve what's in customer carts so that you can offer related products. Extensions use JavaScript to read and write data and call external services, and natively render UIs built using Shopify's checkout components.

Extension APIs

import {
  reactExtension,
  useShippingAddress,
  Banner,
} from '@shopify/ui-extensions-react/checkout';

export default reactExtension(
  'purchase.checkout.delivery-address.render-before',
  () => <Extension />,
);

function Extension() {
  const {countryCode} = useShippingAddress();

  if (countryCode !== 'CA') {
    return (
      <Banner>
        Sorry, we can only ship to Canada at this
        time
      </Banner>
    );
  }
}

import {
  extension,
  Banner,
} from '@shopify/ui-extensions/checkout';

export default extension(
  'purchase.checkout.delivery-address.render-before',
  (root, api) => {
    renderApp(root, api);

    api.shippingAddress.subscribe(() =>
      renderApp(root, api),
    );
  },
);

function renderApp(root, api) {
  const {countryCode} =
    api.shippingAddress.current;

  // In case of a re-render, remove previous children.
  for (const child of root.children) {
    root.removeChild(child);
  }

  if (countryCode !== 'CA') {
    const banner = root.createComponent(
      Banner,
      {},
      'Sorry, we can only ship to Canada at this time',
    );
    root.appendChild(banner);
  }
}

UI components

UI components

Checkout UI extensions declare their interface using supported UI components. Shopify renders the UI natively, so it's performant, accessible, and works in all of checkout's supported browsers. Checkout components are designed to be flexible, enabling you to layer and mix them to create highly-customized app extensions that feel seamless within the checkout experience. All components inherit a merchant's brand settings and the CSS cannot be altered or overridden.

UI components

import {
  reactExtension,
  BlockStack,
  InlineStack,
  Button,
  Image,
  Text,
} from '@shopify/ui-extensions-react/checkout';

export default reactExtension(
  'purchase.checkout.block.render',
  () => <Extension />,
);

function Extension() {
  return (
    <InlineStack>
      <Image source="/url/for/image" />
      <BlockStack>
        <Text size="large">Heading</Text>
        <Text size="small">Description</Text>
      </BlockStack>
      <Button
        onPress={() => {
          console.log('button was pressed');
        }}
      >
        Button
      </Button>
    </InlineStack>
  );
}

import {
  extension,
  BlockStack,
  Button,
  Image,
  InlineStack,
  Text,
} from '@shopify/ui-extensions/checkout';

export default extension(
  'purchase.checkout.block.render',
  (root, api) => {
    const inlineStack = root.createComponent(
      InlineStack,
      {},
      [
        root.createComponent(Image, {
          source: '/url/for/image',
        }),
        root.createComponent(BlockStack, {}, [
          root.createComponent(
            Text,
            {size: 'large'},
            'Heading',
          ),
          root.createComponent(
            Text,
            {size: 'small'},
            'Description',
          ),
        ]),
        root.createComponent(
          Button,
          {
            onPress: () => {
              console.log('button was pressed');
            },
          },
          'Button',
        ),
      ],
    );

    root.appendChild(inlineStack);
  },
);

Security

Security

Checkout UI extensions are a safe and secure way to customize the appearance and functionality of the checkout page without compromising the security of checkout or customer data. - They run in an isolated sandbox, separate from the checkout page and other UI extensions. - They don't have access to sensitive payment information or the checkout page itself (HTML or other assets). - They are limited to specific UI components and APIs that are exposed by the platform. - They have limited access to [global web APIs](https://github.com/Shopify/ui-extensions/blob/unstable/documentation/runtime-environment.md). - Apps that wish to access [protected customer data](/docs/apps/store/data-protection/protected-customer-data), must submit an application and are subject to strict security guidelines and review proccesses by Shopify.

Troubleshooting

Troubleshooting

Find an end-to-end guide to testing your extensions in [Testing checkout UI extensions](/apps/checkout/test-ui-extensions#test-the-extension-in-the-checkout-editor). If you're encountering errors when you run `dev` for an app that contains checkout UI extensions, follow this [troubleshooting guide](/apps/checkout/delivery-instructions/getting-started#troubleshooting).

Resources

Resources