Section-aware comparison
When one section grows or a new one is added, only that section is marked — the pages line up again below it, so one banner doesn’t flag the whole page.
Chrome Extension Publishing soon
Site Visual Diff Tool
Compare production and staging page by page. See every layout shift in red.
Coming soon to Chrome
See how it works
3
Compare views
1440px
Default viewport
50
Pages per scan (default)
0
Bytes uploaded
Made for the moment
before you hit publish
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Before you push an update
Check staging against production before it goes live.
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After theme or plugin updates
Catch layout breaks from a theme, plugin or page-builder update.
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After a migration
Confirm the site looks the same after a move or a change of host.
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During a redesign
Review a redesign page by page instead of clicking around.
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Hunting broken links
Find broken links and images, and see which ones are new on staging.
3 steps, one button
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1
Enter two domains
Open the side panel, add a Base Domain (usually production) and a Comparison Domain (usually staging), and start a deep scan. It opens each page on both domains, waits for images, hides popups and captures full-page screenshots while a live log shows progress.
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2
Read the report
When the scan finishes, every page is listed as Identical or Visual Shift Detected with the share of pixels that changed — plus the broken links found on both sites.
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3
Compare any page
Open a flagged page to see baseline, comparison and diff side by side, or drag the slider between them. Export the report for a colleague.
Every view, up close
What you get
Full-page screenshots
Stitched from scrolled captures, or first screen only for faster scans.
Three ways to compare
Side by side, a drag slider, or the diff image with changed pixels in bright red.
No popup noise
Popups, cookie banners and chat widgets are hidden with CSS before each screenshot. It never clicks Accept for you.
Broken link check
Internal links, external links and images on both sites. Links that refuse automated checks are listed as “could not verify”, not broken.
Export & share
A report file a colleague can open in the extension, plus CSV files for pages and broken links.
Report you can work through
Filters, path search, sorting by largest difference, and notes for pages that error on the comparison site or differ in height.
What leaves
your computer?
Only the requests you ask for. Screenshots and results stay in your browser and are replaced by the next scan. There is no Mellocity server on the other end.
Read the privacy policyYour browser
Local storage
ScreenshotsResultsSettings- Base domaine.g. production
- Comparison domaine.g. staging
- Links on those pagesonly if link check is on
- Mellocity serversnone exist
Options & permissions
Scan options
Tune each scan from the side panel.
- Page limit
- 50 pages by default
- Render delay
- 2 seconds, so page-builder CSS and web fonts finish loading
- Viewport width
- 1440 px by default
- Sensitivity
- Share of changed pixels above which a page is flagged
- Broken link check
- All links, internal links only, or off
- Deep crawl
- Follow links found on sub-pages
Permissions, explained
Chrome lists these when you install. Here’s what each one is used for.
tabs- Opens a temporary scan window with two tabs and reads their URL and loading status, so it knows when a page has loaded or redirected.
scripting- Reads internal links, measures page height, scrolls for full-page capture and pauses animations — only in the two tabs it opens.
storage- Saves your scan settings and the latest results locally so the report can be reopened.
unlimitedStorage- Full-page screenshots are kept locally in IndexedDB; a scan of 50+ long pages can exceed the default quota.
sidePanel- Shows the domain fields, scan options and progress log in Chrome’s side panel.
<all_urls>- You choose the two sites, so they can’t be known in advance. The link check also reads the HTTP status of links found on those pages.
Questions, answered
Is it free?
Yes. There is no paid plan and no account.
Does it upload my screenshots anywhere?
No. Everything runs in your browser. Screenshots and results are stored locally on your computer and replaced by the next scan. There are no servers, no account and no analytics.
How does it decide a page has changed?
It compares the two full-page screenshots section by section and flags the page when the share of changed pixels is above the sensitivity you set.
Can I share the results with my team?
Yes. Export creates a report file a colleague can open in the extension, plus CSV files for pages and broken links. Share it only with people who may see those pages.
Which browsers does it support?
Google Chrome 116 or newer, on any desktop operating system.
