● Covered by 1 source · 1 reportMedium impact1 neutral
Shopify Rebuilds Checkout Blocks with Polaris Web Components, Reduces Bundle Sizes
Key points
- Shopify rebuilt five Checkout Blocks UI extensions.
- Extensions now use Preact and Polaris web components.
- Bundle sizes decreased by 40-85%, load times improved.
- API version 2026-01 is mandatory from October 1, 2026.
Checkout Blocks Rebuilt
Shopify detailed the rebuilding of its Checkout Blocks app, specifically five high-traffic checkout UI extensions. These extensions were moved from React and the legacy Remote UI bridge to remote-dom, utilizing Preact and Polaris web components. The rewrite involved updating to TypeScript and migrating from API version 2025-07 to 2026-01.
Performance Improvements
The migration resulted in significant performance gains. Transferred bundle sizes for the extension family decreased by 40 to 85 percent, with the payment-icons extension seeing an 84.4 percent reduction. Extension Load Time dropped approximately 8 percent at the median and 7 percent at the 90th percentile, weighted by checkout volume. This was largely due to a 64KB gzip budget enforced by the 2026-01 remote-dom CLI.
Technical Changes
Key technical changes included switching from React to Preact, which removed react-reconciler and saved about 89KB. The liquidjs library (73KB) was replaced with an in-house Liquid parser called "droplet" (13KB gzipped). A custom date utility replaced dayjs, while markdown-to-jsx was retained and aliased onto Preact.
Mandatory Update and Developer Resources
The update to API version 2026-01 is mandatory, with app deployments including earlier extension versions being blocked from October 1, 2026. Shopify provides upgrade guides and an AI toolkit, along with specific migration guides for Checkout and Customer Account extensions, to assist developers with this transition.
Industry Reception
The broader shift to Preact and framework-agnostic web components, first introduced with the API 2025-10 release, initially received positive feedback. Developers noted Preact's React-like experience with a smaller runtime and welcomed the use of web components without Shadow DOM. However, as the 2026-01 version became mandatory, some developers expressed mixed sentiment regarding aspects like unversioned CDN scripts.
✨ This summary was generated by AI from the outlets' reporting listed below. It is not independently verified and may contain errors — check the original sources. How BrevFeed works →
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Reporting from
Shopify rebuilt five high-traffic Checkout Blocks UI extensions using remote-dom with Preact and Polaris web components, moving from React and a legacy bridge. This change reduced bundle sizes by 40-85% and improved extension load times, with API version 2026-01 becoming mandatory for app deployments from October 1, 2026.