Compare Images

Add a before and an after image. Compare them with a slider, side by side, as a fade, or as a difference map that marks every changed pixel in red.

Free. Runs in your browser; files are not uploaded.

Before image

Drop one image, or both at once.

After image

Drop the changed version.

Runs locally in your browser. Files are processed on this device and are not uploaded.

How to compare two images

Add two images
Choose the before image first, then the after image. Swap reverses them.
Pick a view
Slider, Side by side, Fade or Difference. Each view updates at once.
Inspect the change
Drag the slider, set the fade, or read the count and area of changed pixels in Difference view.
Save the comparison
Select Download PNG to save the current view as comparison.png.

View	Shows	Best for
Slider	Before on the left, after on the right of a movable line	Layout and color changes
Side by side	Both images next to each other	Reviews and reports
Fade	The after image over the before image at an opacity you set	Small shifts in position
Difference	Changed pixels in red over a light gray copy	Finding every changed pixel

A pixel counts as changed when any color channel differs by more than 10% (about 26 of 255 levels). This ignores tiny compression noise.

By default the after image is scaled to the width of the before image. Choose Actual size to compare pixels without scaling.

No. The comparison is drawn in your browser and both images stay on your device.

The view on screen at full resolution. Side by side is twice the width of the before image.

Temposhot captures a list of URLs on your Mac with the same settings each time, so the before and after shots line up.

Free download. Apple Silicon, macOS 14 or later.