UI extensions using API version 2025-10 or later are limited to a 64 KB compressed JavaScript bundle per extension. Full page customer account extensions may use up to 128 KB. If your extension remains over the limit after optimization, run shopify app build and submit the minified bundle and its esbuild metafile through the bundle size exception form.
Shopify will review the contents of your bundle and may grant a limit increase if the remaining bundle weight is unavoidable.
Requests will be denied for avoidable bundle weight, including heavy libraries, duplicate dependencies, and translations bundled with the extension instead of provided through the native localization APIs.
To remain deployable after October 1, 2026, an app must ensure that every existing UI extension uses API version 2026-01 or later.
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