How the crop tool handles your photo
This page works on a canvas that is the exact pixel size of the photo you drop, so what you see is the real image, not a scaled preview that gets re-sampled later. Drag anywhere across the picture and a rectangle follows the pointer; the area outside is dimmed so you can judge the composition. Release, and the rectangle becomes the crop. Drag again to replace it, or press Reset crop to clear it. If you never draw a rectangle, Download exports the whole image, which makes the page a quick way to rotate or mirror a photo without cropping at all.
Rotation is in 90 degree steps, left or right, and there are separate horizontal and vertical flips. Each of those operations redraws the canvas and clears any pending crop, so the usual order is: rotate or flip first, then draw the crop, then download. Tiny accidental drags under four pixels are ignored rather than producing a one pixel crop.
Cropping is lossless, the export is not always
Selecting a region and cutting it out does not change the pixels inside the region. The only thing that can alter quality is the final encode, and that depends on the format you choose in the dropdown. PNG is lossless and keeps transparency, so a cropped logo or screenshot comes out pixel-identical to the source. JPEG and WebP are written through the browser's own encoder at a fixed quality of 92, which is high enough that a second visible generation of artefacts is unlikely, but it is still a lossy step.
A practical example: a 6000x4000 camera JPG of 9 MB, cropped to a 3000x2000 detail, typically becomes a 1.5 to 2.5 MB JPEG or a 1 to 1.8 MB WebP, and a 12 to 18 MB PNG. Those are typical numbers; a busy texture pushes them up, flat sky pushes them down. If the file has to be small as well, run the crop through the compressor afterwards, where you control the quality yourself.
Transparency and metadata
If the source is a PNG or WebP with a transparent background, choose PNG or WebP on export. JPEG cannot store an alpha channel, and the browser fills the transparent area with black when it writes a JPEG, which is rarely what you want. The canvas export also drops all metadata: EXIF orientation, camera make, lens, timestamp, GPS, and the embedded colour profile. That is a privacy plus, but a photo with a wide gamut Display P3 profile may look slightly flatter once it is re-saved as plain sRGB. For photos where the original metadata matters, keep the source file and treat the crop as a derived copy.
Photos taken in portrait orientation are auto-rotated by the browser when they load, so they appear upright on the canvas. The rotate buttons are for the cases where that did not happen or you want a deliberate turn.
Limits worth knowing
There is no aspect ratio lock and no numeric input, so you cannot type 1080x1080 here. For exact social sizes use the resize tool, which has presets and a crop-to-fill mode. Rotation is limited to right angles; there is no free-angle straightening of a tilted horizon. HEIC files from an iPhone will not load directly in most browsers; convert them on the HEIC to JPG page first. And because the canvas holds the full image in memory, a 100 megapixel scan can exceed what a phone browser will allocate, while a normal laptop handles it without issue. Nothing is uploaded at any stage; close the tab and the image is gone.