Updated 20 October 2026 · Page Mix
Work on a copy
- Upload or duplicate the theme as an unpublished theme, and keep your current theme in the library as a fallback.
- Preview with real products, using the theme preview, before publishing.
Buying works
- Every variant can be selected, and the price, availability and image update correctly.
- Add to cart works, the cart shows the right item, and checkout starts.
- Sold-out variants are handled, and products without variants still work.
- Subscriptions, bundles or upsell apps you rely on appear on the new template. App blocks must be added per template.
Mobile and layout
- Check on a real phone: nothing overflows sideways, tap targets are easy to hit, and the buy button is easy to find.
- Long headlines and translated text don't break the layout.
- Images have sensible sizes and crops at every width.
Content and rights
- Every placeholder is replaced. Search the preview for words like "Insert" or "Add".
- All text, images and claims are yours or licensed. Generated pages that copy another site's content can create legal problems.
- Product claims (health, environmental, "best") are accurate and allowed where you sell.
Speed
- Run the product URL through PageSpeed Insights before and after. Watch for oversized images and extra scripts.
- Large images are compressed, and images below the first screen load lazily.
Accessibility
- Images have descriptive alt text, and decorative images don't.
- Text has enough contrast with its background.
- The page can be used with a keyboard, and the heading order makes sense (one main heading, then sub-headings).
SEO settings
- The product title and description, and the SEO title and meta description in Shopify's product editor, are set.
- The page has one main heading, usually the product name.
- Changing a template doesn't change the product URL, so existing links and rankings are kept.
Code quality
- Run Shopify's Theme Check, or look for errors in the theme editor. Theme Check catches many Liquid problems.
- Check the browser console on the preview for JavaScript errors.
How Page Mix handles this. Page Mix checks that each section renders, in order, on mobile, and validates the whole theme before you download it. You still need to check your own products, apps and content, which only you can do.