How does cropping an image work?
Drop a single photo onto the page, or pick one from your device. A box appears over the image, and you drag its edges and corners to frame the part you want to keep. When the framing looks right, press the button and everything outside the box is trimmed away. The cropped image is ready to download in seconds. There is nothing to set up first, and the photo stays on your own machine the whole time, nothing is sent to a server.