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Pixel diff
Image Difference Checker
Compare two images for differences, pixel by pixel. Changed pixels are highlighted over a dimmed original, you get an exact similarity percentage, and one click publishes a permanent share link anyone can open - handy in pull requests, bug reports and design reviews.
The checker runs an image diff directly in your browser: both files are decoded to raw pixels and compared position by position, with a built-in tolerance for antialiasing so font smoothing does not drown out real changes. Nothing is uploaded while you compare. Byte-identical files are confirmed by checksum, not eyeballing. Publishing has a 20 MB per-image cap (50 MB with Pro), and images past 16 million pixels are compared on a scaled copy - the tool says so when it happens.
Four views cover the usual workflows: the differences overlay, side by side, the interactive slider imgi is known for, and a flicker mode that blinks the two images in place. The sensitivity slider re-runs the comparison live, a hover loupe shows the actual pixels and RGB values of both images, and ignore regions let you exclude timestamps or ads from the comparison entirely. Same-size screenshots compare 1:1 exact, which is what makes it a dependable screenshot diff tool: a shifted button or a broken icon shows up as a crisp magenta region.
Need presentation rather than analysis? The imgi slider or the fully offline local compare may fit better.
Common questions
01How do I find differences between two images?+
Drop, choose or paste both images into the checker above. It compares them pixel by pixel and paints every changed pixel in magenta over a dimmed copy of the first image, so even a one pixel shift stands out. You can also flip to a side by side view, an interactive slider, or a flicker view that blinks the two images in place.
02Can I exclude parts of the image from the comparison?+
Yes. Click “Ignore region” and drag a rectangle over anything that changes on every capture - timestamps, ads, blinking cursors, animated elements. The comparison recomputes without those areas, they are hatched in the view and in the downloaded diff, and they travel with the share link.
03What is image similarity percentage?+
It is the share of pixels that stayed the same between the two images. If 990,000 of 1,000,000 pixels are unchanged, the images are 99% similar. The checker shows this number live and recalculates it when you adjust the sensitivity.
04Are my images uploaded when I compare them?+
No. The comparison runs entirely in your browser. Images are only uploaded if you choose to publish the result for a share link, and you can make that link private with imgi Pro.
05Can I use this as a screenshot diff tool?+
Yes, that is what it is best at. Screenshots from the same window size compare 1:1, so UI regressions, rendering glitches and copy changes light up immediately. Publish the result and paste the link straight into a bug report or pull request.
06What does the sensitivity slider do?+
It sets how big a color change counts as a difference. At high sensitivity the checker flags subtle shifts like JPEG compression noise; lower it to ignore noise and antialiasing so only real changes remain.
07What image formats work?+
JPEG, PNG, GIF, WebP and AVIF. The two images do not need to match in format, and if their dimensions differ the second image is scaled to fit the first so you still get a comparison.
08Why does a small shift show huge differences?+
Because a pixel comparator compares positions, not shapes. If the second image is shifted by one pixel, nearly every edge lands on a different position and the tool honestly reports a large difference. That is correct behavior for catching layout movement; to judge shifted content by eye, use the Slider or Flicker view instead.
09What are the limits?+
Comparing runs in your browser with no account and no daily cap. Images over 16 million pixels are compared on a scaled copy, and the tool tells you when that happens instead of pretending otherwise. The per-image size cap only applies when you publish a share link.