Shopify Theme Migration Checker

Switching Shopify themes can break performance, layouts, and SEO. Cutover runs a before-and-after scan to validate Core Web Vitals, screenshots, redirects, and missing pages before you publish.

Compare current theme vs new theme
Run scans against preview themes
Measure Core Web Vitals (LCP, CLS, TBT)
Capture full-page screenshots
Export reports for clients and stakeholders

Free trial includes up to 15 URLs. No credit card required.

Compare your live Shopify theme against a preview theme — validate performance, Core Web Vitals, and visual differences before publishing.

Domain

Comparison Type

Shopify: Live theme vs preview theme

Compare your published Shopify theme against an unpublished preview

Shopify: Compare two preview themes

Advanced: compare two unpublished Shopify themes against each other

Live site vs custom query string

Any platform — compare using a query parameter (A/B tests, feature flags)

Preview Theme ID

Find this in your Shopify admin: Online Store → Themes → Customize. The theme ID is the number in the URL after /themes/.

Theme comparison includes:

✓ Core Web Vitals delta (LCP, CLS, TBT)
✓ Full-page screenshot comparison
✓ Asset weight & resource changes
✓ Template rendering differences
✓ Performance (TTFB, load time)

5 credits/URL · Free up to 15 URLs

Screenshot Viewport

Max URLs to Check

Free trial: up to 15 URLs (5 credits/URL)

Common Shopify theme migration issues

A Shopify theme change is effectively a full site rebuild. Even if URLs stay the same, performance and layout can change dramatically.

LCP regression from large hero images

CLS issues from font loading or layout shifts

Apps injecting scripts and slowing down TBT

PDP template issues (missing sections)

Collection filtering breaking

Broken navigation links

What Cutover checks during a theme migration

Core Web Vitals (LCP, CLS, TBT)

Full-page screenshot comparisons

TTFB and total load regression

Page size and asset weight changes

Missing pages and broken links

Redirect destination accuracy

CSS / JS differences

Sitemap vs crawl discovery gaps

Recommended scan settings for Shopify theme rebuilds

Scan Type:Theme Comparison

Comparison:Live vs preview theme

Preview Theme ID:From Shopify Admin → Online Store → Themes

Max URLs:Start with 10–25 high-value pages

Viewport:Desktop (1280×720) or Mobile (375×812)

Select Theme Comparison above, enter your domain and preview theme ID. Cutover automatically compares your live theme against the preview—no need to enter the domain twice or manually configure query strings.

Cutover catches problems Lighthouse won't

Cutover is designed for side-by-side comparisons across many URLs. Instead of manually checking pages one at a time, you can run a structured audit and export results in minutes.

Web Vitals across multiple pages
Screenshot grid for visual QA
Performance regression detection at scale

Shopify Theme Migration FAQ

Also works for other migrations

While this page focuses on specific platform migrations, Cutover works with any platform that exposes accessible URLs. You can use it to compare any two domains or validate performance before and after major site changes.

Magento migrations

Webflow rebuilds

WordPress redesigns

Domain changes

HTTP → HTTPS migrations

Publish your new theme with confidence

Run a free scan and catch Core Web Vitals regressions before launch day.

More migration tools

Shopify migration checker WooCommerce → Shopify migration checker BigCommerce → Shopify migration checker All migration tools Start a scan

Cutover is a Shopify theme migration testing tool designed to compare Core Web Vitals, capture full-page screenshots, detect performance regressions, and validate page rendering before publishing a new theme.