Online Visual HTML Comparator
The only tool that compares your web pages visually, pixel by pixel. Go beyond simple text diffs: detect CSS rendering, layout and style differences that code alone cannot reveal.
Visual comparison, not textual
Unlike classic HTML diff tools, Delta-QA renders both pages in a real browser and compares the visual output pixel by pixel. CSS differences invisible in code become obvious.
Intelligent change detection
Our algorithm identifies added, removed, modified and moved elements. Each difference is ranked by visual impact with a strength score to filter noise.
Instant similarity score
Get a global similarity percentage and precise difference counts. Ideal for visual regression, front-end code review and quality assurance.
How does visual HTML comparison work?
Paste your HTML or enter your URLs
Insert the HTML code of your two versions or enter the URLs of the pages to compare. URL mode loads pages in real time in a Chromium browser.
Automatic rendering and analysis
Delta-QA renders each page in a real browser, extracts the DOM and screenshots of every element, then runs a 5-pass structural matching algorithm.
View highlighted differences
Results display side-by-side with modified elements highlighted directly in the page. Adjust sensitivity and color to explore every detail.
Frequently asked questions about HTML comparison
Why is a classic HTML diff not enough to detect visual bugs?
A text diff compares source code line by line but ignores CSS rendering differences. Delta-QA renders both pages in a real browser and compares the result pixel by pixel, detecting the real differences users see on screen — not just code changes.
Which online HTML comparator is free and requires no signup?
Delta-QA online HTML comparator is completely free and requires no signup. Paste your HTML code or enter your URLs and launch the visual comparison immediately.
How to visually compare staging and production before a deployment?
Enter your staging URL and production URL in Delta-QA URL mode. Each page is loaded in a headless Chromium browser and compared pixel by pixel. Ideal for verifying a deployment has not introduced visual regressions.
What types of CSS differences can a visual comparison tool detect?
The algorithm detects 5 types of changes: added elements, removed elements, visually modified, moved within the page, and moved with modification. Each signal has a strength score (0-100%) to filter minor changes.
How to verify a CSS update has not broken other pages?
Use Delta-QA to compare the page before and after your CSS update. The visual comparison detects subtle differences (margins, fonts, colors, spacing) invisible in a text diff. The ideal tool for front-end developers, QA engineers and designers.
How to verify a redesign has not broken other pages?
Compare your pages before and after the redesign with Delta-QA. The 5-pass structural matching algorithm detects every visual change: shifted elements, modified styles, missing components. Review differences one by one with highlighted overlays.
Can you compare two web pages across different browsers?
Delta-QA URL mode renders pages in a Chromium browser. To compare cross-browser rendering, use the Delta-QA desktop application which supports multi-browser visual comparison across Chrome, Firefox, and WebKit.