Merchants use [Shopify checkout](https://help.shopify.com/manual/checkout-settings) to accept orders and receive payments wherever they sell online. You can augment Shopify checkout with new functionality by building an app.
## How it works
After a customer adds products to a cart, they use Shopify checkout to enter their customer, shipping, and payment information before placing the order.
Developers can create apps that extend Shopify checkout to include functionality that isn't provided natively. For example, you can create an app that offers a customer free shipping or other discounts depending on what's in their cart.
Merchants install these apps on their store in the Shopify admin. In the Shopify admin, merchants can use the [checkout editor](/docs/apps/build/checkout/test-checkout-ui-extensions#test-the-extension-in-the-checkout-editor) to place a [checkout UI extension](/docs/api/checkout-ui-extensions) in the checkout experience.
## Customization options
You can customize Shopify checkout using multiple technologies. All customization options are easy to install and upgrade-safe, which enables merchants to continue getting platform benefits when Shopify releases new products such as [Shop Pay](/docs/apps/build/checkout/test-checkout-ui-extensions#test-with-shop-pay), or features such as [One-page checkout](/docs/apps/build/checkout/test-checkout-ui-extensions#one-page-checkout).
For a detailed breakdown of the available technologies for customizing checkout, and ways that you can extend checkout, refer to the [options for customizing Shopify checkout](/docs/apps/build/checkout/technologies).
## Getting started
Learn how to customize and extend checkout by following one of our use case tutorials.
### Checkout UI extensions tutorials
## Upgrade
> Deprecated:
> `checkout.liquid` is now unsupported for the Information, Shipping, and Payment checkout steps. 'checkout.liquid', additional scripts, and script tags are deprecated for the **Thank you** and **Order status** pages and will be sunset on August 28, 2025.
> Stores that currently use `checkout.liquid` for the **Thank you** and **Order status** pages need to [upgrade to Checkout Extensibility](https://www.shopify.com/plus/upgrading-to-checkout-extensibility) before the deadline. [Shopify Scripts](/docs/api/liquid/objects#script) will continue to work alongside Checkout Extensibility until August 28, 2025.
A report identifying your current checkout customizations is available in the Shopify admin. The report provides high-level guidance to map customizations to Checkout Extensibility. Use this report to simplify your review of your existing customizations and to help you upgrade to Checkout Extensibility faster. [Learn more](https://help.shopify.com/en/manual/checkout-settings/checkout-extensibility/checkout-upgrade).
To upgrade a `checkout.liquid` customization to Checkout Extensibility, take one or more of the following actions:
1. Use a public app that's built using extensions.
We're adding new checkout apps to the Shopify App Store on a regular basis. If there currently isn't a suitable public app for your customization, then consider simplifying your checkout temporarily and adding new apps to your store as they become available.
1. Build a custom app using extensions, or [hire a service partner](https://www.shopify.com/plus/partners/service?type=service&services%5B%5D=141) to build one for you.
In some cases, after you've upgraded you can [revert to `checkout.liquid`](https://help.shopify.com/manual/checkout-settings/checkout-extensibility/checkout-upgrade#revert-to-checkout-liquid) until its sunset dates.
If you're upgrading a store to Checkout Extensibility, we recommend planning your in-checkout, **Thank you** page, and **Order status** page upgrades together, when possible, for the following benefits:
- Avoid maintaining multiple tech stacks, like UI extensions and `checkout.liquid`.
- Apply styling once to the entire experience.
- Manage one sunset date for `checkout.liquid` rather than one date for pre-purchase pages and another for **Thank you** and **Order status** pages.
If this isn't possible, then we recommend prioritizing the upgrade for in-checkout pages first and upgrading after-purchase pages after that.
## Best practices
To optimize your app development experience, Shopify has established a set of best practices that you can refer to when developing an app that extends checkout.
> Tip:
> We also recommend getting familiar with Polaris [accessibility](https://polaris.shopify.com/foundations/accessibility) and [content](https://polaris.shopify.com/content/merchant-to-customer) guidelines.
## Product roadmap
Some checkout customization features are in development and will be released later this year. The following are the features on our roadmap and our estimated launch dates:
> Note:
> This roadmap is being shared for informational purposes and is subject to change. Bug fixes and improvements will be added as we hear from the community. Share your feedback or request new features by creating a new issue in the [Shopify developer community forum](https://community.shopify.dev/).
### UI extensions
Stores that subscribe to the Shopify Plus plan can add UI extensions to their **Checkout**, **Thank you** and **Order Status** pages. Stores on Basic, Shopify, and Advanced plans can only add UI extensions to their **Thank you** and **Order Status** pages. Merchants can install apps from the Shopify App Store or build custom apps that contain UI extensions.
We'll continue adding API capabilities to help you access the right functionality in extensions. We'll also continue adding UI components that offer performant patterns on our design best practices. We release new components and APIs into the [unstable](/docs/api/usage/versioning#unstable-api-versions) API version first, and promote to the next stable release based on Shopify's [API version release schedule](/docs/api/usage/versioning#release-schedule).
| Feature | Target launch date |
|---|---|
| Checkout and accounts editor setting to [display the discount code field by default](https://help.shopify.com/en/manual/checkout-settings/customize-checkout-configurations/checkout-style#discount-field) on mobile devices | June 2024 (shipped) |
| Support for [conditional component rendering](/docs/api/checkout-ui-extensions/unstable/components/utilities/stylehelper#examples) on mobile checkouts | June 2024 (shipped) |
| Support for [one-time use addresses](/changelog/storefront-api-cart-now-supports-one-time-use-delivery-addresses) in Storefront Cart API and UI Extension API | July 2024 (shipped) |
| Support for UI extensions in [draft order invoice checkouts](/changelog/checkout-ui-extensions-new-required-cart-instructions-api-when-updating-to-2024-07-api-version) | July 2024 (shipped) |
| Default a buyer to a merchant-provided address, with an option for the buyer to enter new address | August 2024 (early access) |
| Support for [conditionally hiding the input field for 1st-party gift cards](/changelog/conditionally-disable-gift-cards-in-checkout-using-custom-logic-with-the-payment-customization-api) | November 2024 (shipped) |
| Support for [styling order summary line items with the Branding API](/changelog/customize-line-items-in-checkout-and-customer-accounts-order-summary-using-new-checkout-branding-api-settings) | December 2024 (shipped) |
| Support for integrating 3rd-party [chat applications](/docs/apps/build/checkout/chat) into checkout | December 2024 (shipped) |
| Support for programmatic overlays on the **Thank you** page and customer account pages | Q1 2025 |
| Support for reading app owned metafields in checkout UI and customer account extensions | Q1 2025 |
| Input query API for customizing the data available to UI extensions | Q2 2025 |
### Shopify Functions
We'll continue to add new Shopify Function APIs to further customize checkout business logic.
| Milestone | Target |
|---|---|
| Addition to the [Product Discount API](/docs/api/functions/reference/product-discounts) to [target cart line items](/docs/api/functions/reference/product-discounts/graphql/common-objects/target?api%5Bversion%5D=2024-07) | Q3 2024 (shipped) |
| Support for cart metafields on function input queries | April 2025 |
| Changes to the [Discount APIs](/docs/api/functions/reference/product-discounts) to stack multiple discounts on the same product line item | Q2 2025 |
### Web pixel app extensions
We'll continue to add new custom pixel and app pixel events and features.
| Milestone | Target |
|---|---|
| Added new standard events: tracking errors during checkout | October 2024 (shipped) |
| Support for extending data fields on standard events | Q1 2025 |