Floating semi-transparent image for comparison

Try this application I just came accross: http://infinite-labs.net/afloat/


Here's a few more:

  • Uberlayer
  • GluePrint
  • Overlay

More alternatives (also for Windows) on alternativeto.net


For any web development purposes or when working in any web app you can use a browser extension like the PerfectPixel by WellDoneCode. It's free and supports multiple overlays.