The cropper tool from Raketten is a very small tool which solves a big problem. Whenever you take a photo of some rectangular shape, like a box or a book. TRaditional cropping will not give you a good result due to the perspective error. Either you have to accept some air around the box, or you have to accept loosing part of your box. This is where Raketten cropper can help you. It lets you select each of the 4 corners and warp your box to show only the box.

The tool does not require an account or any personal information, just install and use.