Image Diff — Pixel Compare

Free

Compare two images pixel-by-pixel and highlight exactly what changed.

Original (A)Modified (B)

Add both images to see the pixel difference. Different sizes are aligned to image A automatically.

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What is Image Diff — Pixel Compare?

Updated July 25, 2026

Image Diff compares two images pixel-by-pixel and highlights exactly what changed — as a difference map, red highlight, or heatmap — plus the percentage of pixels that differ. It aligns different-sized images, runs entirely in your browser, and exports a PNG.

Compare two images and see exactly which pixels changed. Drop an original and a modified version and the tool overlays them, computing a per-pixel difference so you can instantly spot what moved, was added, or was removed — perfect for design reviews, QA, screenshot regressions, spot-the-difference, and verifying edits. Choose a view mode (difference map, red-highlight of changed areas, or heatmap), adjust the sensitivity threshold, and read the exact percentage of pixels that differ. Images of different sizes are aligned automatically, everything is processed locally in your browser, and the result can be downloaded as a PNG.

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Why choose Image Diff — Pixel Compare?

Image Diff provides a fast, client-side way to spot exact pixel changes between two images without installing heavy software or uploading files to a remote server. It features multiple view modes including difference maps, red highlights, and heatmaps, along with automatic alignment for images of different sizes. Users get precise metrics such as the exact percentage of differing pixels and can export the result instantly as a PNG.

Best for

Designers reviewing visual edits and mockups
QA testers checking screenshot regressions
Developers verifying UI implementation against design files
Quickly solving spot-the-difference puzzles

Good to know: Very large image files or highly complex pixel matrices may impact browser performance during local processing.

How to Use Image Diff — Pixel Compare

Learn how to compare two images pixel-by-pixel and instantly spot visual changes using browser-based tools.

1
Upload your original and modified images
Drag and drop both your original image and the modified version into the tool to begin the comparison.
2
Choose a preferred view mode
Select from a difference map, red-highlight of changed areas, or a heatmap to visualize the modifications clearly.
3
Adjust the sensitivity threshold
Fine-tune the sensitivity settings and let the tool automatically align images of different sizes if needed.
4
Analyze results and download PNG
Review the exact percentage of differing pixels and download the final comparison result as a PNG.

Estimated time: PT1M

Frequently Asked Questions

What is Image Diff — Pixel Compare?

Image Diff — Pixel Compare is a web tool that compares two images pixel-by-pixel to reveal exact visual changes. It overlays your original and modified images, computes the precise difference, and calculates the exact percentage of pixels that changed.

How do I compare two images with this tool?

Simply drop your original image and the modified version into the tool. It automatically aligns images of different sizes, and you can switch between viewing modes like a difference map, red-highlight, or heatmap to spot what was added, removed, or moved.

Is Image Diff completely free to use?

Yes, Image Diff is a free tool with zero credit costs. Anonymous users can use it up to 100 times, while authenticated users receive up to 400 uses.

Are my images uploaded to a server or kept private?

Your images remain completely private because everything is processed locally right inside your browser. No files are uploaded to external servers during the comparison process.

Can I export or download the comparison result?

Yes, once the pixel comparison is generated and you have adjusted your sensitivity thresholds and view modes, you can download the final result directly as a PNG file.

What if the two images are different sizes?

You do not need to manually resize your files beforehand. The tool handles different image dimensions automatically by aligning them before computing the pixel-level differences.

What view modes and customization options are available?

You can choose from multiple view modes including a standard difference map, a red-highlight mode for changed areas, or a heatmap. You can also adjust the sensitivity threshold to fine-tune how subtle or drastic the detected changes appear.