Checkout app extensions
Checkout app extensions make it easy for developers to extend their app code into checkout and customize many aspects of the checkout experience. Shopify provides the tools and resources for building checkout UI extensions and post-purchase extensions.
Checkout UI extensionsAnchor link to section titled "Checkout UI extensions"
Checkout UI extensions let you add custom workflows and functionality at defined points of the checkout process, and are built into apps using extension point APIs and UI components.