Image Diff Checker
Free online image diff tool. Compare two images pixel by pixel with adjustable threshold, side-by-side, difference, and heat-map views, plus a changed-pixel percentage. Runs entirely in your browser - no upload.
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What is Image Diff Checker?
Image Diff Checker is a free browser-based tool that compares two images pixel by pixel. It highlights every changed pixel in red over a dimmed grayscale base, reports the changed-pixel percentage, and offers side-by-side, difference, and heat-map views with an adjustable threshold - all processed locally with no upload.
Key Benefits
- Catch visual regressions in UI screenshots before shipping
- 100% private - images never leave your browser
- Objective similarity verdict via changed-pixel percentage
- Threshold control separates real changes from compression noise
- Exportable PNG diff for bug reports, pull requests, and design reviews
Common Use Cases
- •QA teams comparing a fresh build screenshot against a known-good baseline
- •Developers verifying that a CSS refactor changed nothing visually
- •Designers reviewing handoff files against the implemented result
- •Photographers and editors checking the effect of a re-encode or filter
- •Content teams spotting unwanted changes in updated banner artwork
How to Compare Two Images
- Upload both images: Click the Before and After slots to pick the original and modified images from your device. Files stay local - nothing is uploaded.
- Choose a view mode: Pick Difference to overlay changes in red, Heat Map to see change intensity, or Side by Side for a manual visual check.
- Tune the threshold: Raise the threshold slider to ignore invisible noise like anti-aliasing and JPEG artifacts; lower it to catch the subtlest edits.
- Read the stats and export: Check the changed-pixel count and difference percentage for an objective verdict, then download the diff as a PNG to share it.
Key Features
- Pixel-by-pixel comparison that flags every changed pixel in red
- Adjustable 0-255 threshold to filter anti-aliasing and compression noise
- Side-by-side, difference, and intensity heat-map view modes
- Changed-pixel count and difference percentage with instant verdict
- Download the diff as a PNG for bug reports and pull requests