Getting started with post-purchase checkout extensions

In this tutorial, you’ll learn how to do the following tasks:

• Generate a post-purchase extension with Shopify CLI.
• Run the extension locally and test it on a development store.
• Build the extension UI with the component library.
• Authenticate requests from the extension to your app server.
• Deploy your extension code to Shopify.
• Create a version of your extension and publish it.
• Request access to run the post-purchase checkout extension on a live store.

• You're familiar with post-purchase checkout extensions.
• You've created a Partner account and a development store.
• You can place test orders on your development store.

• You've created an app that uses Shopify CLI 3.0 or higher, or you've migrated your existing app so it's compatible with Shopify CLI 3.0 or higher.

To create a post-purchase checkout extension, you can use Shopify CLI, which generates starter code for building your extension and automates common development tasks.

In your app directory, run one of the following commands to create a new post-purchase checkout extension:

You should now have a new extension directory that includes the extension script at src/index.{file-extension}.

Post-purchase checkout extensions in production are hosted and served by Shopify. During development and testing, you need to use a Shopify browser extension to render your local extensions in checkout.

As you're testing, the browser extension automatically updates the checkout URLs.

1. Navigate to your app directory.

2. Either start or restart your server to build and preview your app:

   
   When you run the dev command, the CLI builds and serves your app. It also instructs you through multiple configuration steps. If you've already run dev for this app, then some of these steps are skipped.

   To learn about the processes that are executed when you run dev, refer to the Shopify CLI command reference.

3. Install the Shopify Post-purchase Developer Tools for Chrome browser extension.

4. Open the developer console in a new browser tab by clicking on the link the Shopify CLI printed to the console. Copy the post-purchase extension URL.

   

5. In the browser extension settings, enter the extension URL from the developer console:

   

6. Place a test order in your development store and go through the checkout steps. The post-purchase UI is shown after the payment step, but before the order status page:

The UI components for post-purchase checkout extensions are managed by Shopify to ensure that the checkout is fast, optimized for mobile, and integrated with Shop Pay.

Post-purchase extensions have access to the Checkout::PostPurchase::ShouldRender and Checkout::PostPurchase::Render extension points.

The extensions points API provides helper functions to allow you to calculate potential order totals, update the order, modify metafields, and more.

Update the extension/my-post-purchase-ui-extension/src/index file with the following code. Replace the APP_URL constant, at the top of the file, with your local tunnel URL:

The following sections explain how different parts of the example extension code work.

The Checkout::PostPurchase::ShouldRender handler pre-fetches product data from the server that is running locally. You pass the token and reference ID to the server so that you can verify that the request came from Shopify, and is signed with the same secret key as the app.

The data returned from the server is then stored in the extension's storage.

Shipping costs and taxes are calculated based on the shipping address. The order changes are passed to the calculateChangeset function provided by the API. The returned data is used to update the UI.

The acceptOffer handler posts a request to the server to sign the changes as a JWT token. The request includes inputData.token, which the server uses to verify Shopify's request. The following code calls applyChangeset with the JWT token returned from the server.

Your app requires two endpoints to support the extension. The first endpoint is used to fetch the product data for the upsell. The second endpoint is used to sign the changeset, so Shopify can verify the request to edit the order that came from your app.

1. Navigate to the web directory of your app:

2. Run the following command to install the dependencies required for the app server:

3. Add the following import statements to the web/index.js file:

In web/index.js, define a function that's used to fetch the product data for the upsell. For simplicity, you'll hardcode the product data in this tutorial. The following logic can be replaced with an API call to Shopify or your own database:

You can use the following GraphQL query to fetch the first product in your Shopify store. Update the getOffer function with the data returned from the query, or the information from the product page in your Shopify admin.

In web/index.js, define two endpoints. The first endpoint is used to fetch the product data that you previously defined for the upsell. The second endpoint is used to sign the changeset, so Shopify can verify that the request came from your app.

Both endpoints will verify that the request came from Shopify by checking that the JWT token is signed by the app's secret key.

Add the following code after the app.use(express.json()); and before the app.use("/api/*", shopify.validateAuthenticatedSession()); lines:

You are now ready to test your upsell functionality extension. Refer to Step 2 for testing in these instructions.

When you're ready, you can deploy your extension code to Shopify.

1. Navigate to your app directory.

2. Run one of the following commands:

   To learn about the processes that are executed when you run deploy, refer to the Shopify CLI command reference.

3. Click Enable to preview a draft of your extension in a development store.

   

When you're ready to release your extension to merchants, you can create a version and publish it.

If you want to run the post-purchase checkout extension on a live store, then you need to request access. Before you request access, you need an unpublished app in a development store.

After your access request has been approved, any apps that you distribute through the Shopify App Store also need to be submitted for review in the Partner Dashboard. The review process is slightly different for existing apps and new apps.

For existing apps:

• You need to test your app using an unpublished app in a development store.
• To add the post-purchase checkout extension to a published app, you must submit the unpublished testing app for review in the Partner Dashboard.
• If the new app meets the stated requirements, then it will be approved and the post-purchase extension can be added to your existing published app.

For new apps:

• You need to test your app using an unpublished app in a development store.
• To add the post-purchase checkout extension to a published app, you must submit the unpublished testing app for review in the Partner Dashboard.
• If the new app meets the stated requirements, then it will be approved and listed in the Shopify App Store.

1. From your Partner Dashboard, click Apps.
2. Click the name of the app that you want to change.
3. Click App setup.
4. In the Post-purchase section, on the Access post-purchase extensions card, click Request access.
5. In the Post-purchase page that opens, describe why you're applying for access.
6. You'll see a banner that your request is under review. The review process can take up to seven days.

After your request is approved, you're notified in the Partner Dashboard that your app has full access to the post-purchase extensions.

• Learn how to create a post-purchase subscription upsell.
• Review the post-purchase extensions points API reference.