The deprecation of Checkout.liquid stems from the introduction of more robust and exclusive benefits for merchants adopting Checkout Extensibility. Shopify merchants embracing Checkout Extensibility can tap into the latest checkout features, including Shop Promise, pre-orders, and a streamlined one-page checkout process. Moreover, they gain access to powerful tools like Checkout Editor, Branding API, Shopify pixel manager, and other Shopify functions, elevating their store's overall performance.
For instance, Checkout.liquid typically works well with express payment as Shop Pay; however, the customizations made to the checkout page using Checkout.liquid may not function seamlessly to Shop Pay, potentially impacting the customer's checkout experience negatively.
In contrast, opting for Checkout Extensibility enables merchants to customize Shop Pay to align seamlessly with all other checkout page customizations. The full integration of Checkout Extensibility with Shop Pay ensures a cohesive and comfortable checkout process for customers.
Crucially, Checkout Extensibility stands out by being powered by a set of Shopify UI components and APIs functioning within a sandboxed environment, ensuring not just feature richness but also an added layer of security—a feature not present in Checkout.liquid.