Image Diff Comparison
Spot pixel-perfect differences via Slider, Side-by-Side, or Difference Overlay.
More Comparison & Analysis Tools
Pixel-Perfect Image Comparison for Pros
In the world of digital design, web development, and photography, the difference between "good" and "ship-ready" often comes down to individual pixels. A barely visible shift in alignment, a subtle change in color grading, or a minor degradation from compression can undermine the quality of your work.
The Image Diff Checker is a professional-grade analysis tool designed to spot these imperceptible differences instantly. Unlike standard image viewers that rely on your memory as you switch tabs, our tool provides four specialized comparison modes—Slider, Fade, Side-by-Side, and Difference Overlay—to visualize changes with mathematical precision.
Whether you are performing Visual Regression Testing for a UI component, checking if a compression algorithm destroyed your image quality, or simply choosing between two similar photos, this tool gives you the objective data you need to make the right decision. Best of all, it runs entirely in your browser, ensuring your sensitive assets never leave your device.
How to Spot Differences
Load Images
Drag and drop your "Before" and "After" images. We support PNG, JPG, WebP, and SVG formats.
Choose Mode
Select from Slider (Swipe), Fade (Blink), Side-by-Side (Sync Zoom), or Difference (Math) modes.
Analyze
Zoom in to inspect pixel-level details. The changes will be highlighted for instant verification.
Professional Comparison Modes
Difference Overlay
Calculates the RGB difference between pixels. Identical areas turn black, while changed pixels glow in neon colors. Perfect for spotting 1px shifts.
Fade / Blink Mode
Rapidly fades between the two images. This "blink comparator" technique relies on human motion perception to catch subtle layout changes.
Synchronized Zoom
In Side-by-Side mode, zooming or panning Image A automatically moves Image B. Compare specific details without realignment.
Interactive Slider
The classic "Before/After" handle. Drag it across the image to see how the change transforms the composition.
Who Needs Visual Regression?
Frontend Developers
Verify that CSS refactors haven't caused unintended layout shifts or regressions.
UI/UX Designers
Ensure the engineering team implemented your Figma designs pixel-perfectly.
Image Optimization Experts
Compare original vs. compressed images to find the perfect balance between size and quality.
QA Engineers
Automate visual testing checks and validate cross-browser consistency.
Frequently Asked Questions
How does the 'Difference' mode work?
The Difference mode calculates the mathematical difference between the RGB values of every pixel in both images. Identical pixels turn black (0 difference), while changed pixels light up in bright magenta/neon colors, making even the tiniest 1-pixel shift instantly visible.
Do the images need to be the same size?
Ideally, yes. If your images are different sizes, our tool will align them by the top-left corner. For the best 'Diff' results, crop your images to match dimensions before uploading.
What is Side-by-Side Synchronized Zoom?
In Side-by-Side mode, when you zoom or pan on Image 1, Image 2 automatically follows. This allows you to inspect specific details (like compression artifacts or text rendering) on both images simultaneously without having to manually align them.
Can I use this for testing compression quality?
Absolutely. Upload your original PNG as Image 1 and the compressed JPEG/WebP as Image 2. Use the 'Slider' or 'Difference' mode to see exactly where quality loss has occurred.
Are my images uploaded to a server?
No. All comparison happens locally in your browser using HTML5 Canvas technology. Your sensitive design mockups or screenshots never leave your computer.
What file formats are supported?
We support unlimited comparisons for PNG, JPEG, WebP, GIF, and SVG files. As long as your browser can display it, we can compare it.
Why is the background dark?
We use a neutral dark studio background (bg-stone-900) to maximize visual contrast. This prevents eye strain and ensures that your perception of color differences isn't biased by a bright white surround.
Is this tool free for commercial use?
Yes, Image Diff Checker is completely free for freelancers, agencies, and enterprise usage. There are no watermarks on the view.
Can I drag and drop images?
Yes! You can drag two images at once onto the canvas, or drag them individually into the respective drop zones.
Does it work on mobile?
Yes, the tool is fully touch-responsive. You can swipe the slider with your finger and pinch-to-zoom in comparison modes.