Online Tool Store
Image Diff Checker
Compare two images pixel by pixel with an adjustable sensitivity threshold, highlighting differences in red with a percentage summary.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Lower catches smaller differences; higher ignores minor compression noise.
How the image diff checker works
- Choose two images to compare.
- Adjust the sensitivity slider to control how much color difference counts as "different."
- Click Compare images — differing areas are highlighted in red over a dimmed version of the first image, with a percentage summary.
How pixels are compared
For every matching pixel position, the tool measures the color distance between the two images' red, green, and blue values (using standard Euclidean distance in RGB space). Any pixel whose distance exceeds your chosen sensitivity threshold is marked as different; everything else is shown dimmed as visual context.
FAQ
What does the sensitivity slider actually control?
It sets how different two pixels' colors need to be before they're flagged as a difference. A low sensitivity flags almost any color variation, including minor JPEG compression artifacts; a higher sensitivity ignores small variations and only flags genuinely different areas.
What happens if the two images are different sizes?
The comparison canvas is sized to the larger of the two images' dimensions — any area only covered by one image (because the other is smaller) will show up as a difference, since there's nothing to compare it against.
Can this compare screenshots for visual regression testing?
It works well for spotting visual differences between two screenshots, similar to what visual regression testing tools do — though this is a manual, one-off comparison rather than an automated testing pipeline.
Are my images uploaded anywhere?
No. Both images are compared entirely in your browser using an HTML canvas — nothing is sent to Online Tool Store or any other server.
How we compare
| Feature | Online Tool Store | Resemble.js online demo | Manual side-by-side viewing |
|---|---|---|---|
| Adjustable sensitivity | ✓ | ✓ | Not applicable |
| Percentage difference summary | ✓ | ✓ | Subjective only |
| Images never uploaded to a server | ✓ | ✓ | ✓ |
For a quick pixel-level comparison with visual highlighting, the Online Tool Store Image Diff Checker spots differences your eyes might miss.