If you’re seeing this, it means that JavaScript failed to load or you otherwise have JavaScript disabled.
While I respect this, you gotta know that this entire tool only works with JavaScript.
Like, it doesn’t call out to my server at all (see the source of imgcrop.js).
So, rather than display a form that won’t work and could frustrate you, this is displayed instead.
File
FFmpeg crop command
ffmpeg -i input -vf "crop=out_w:out_h:x:y" out.webp
Warning: This won’t auto-orient images that are rotated through EXIF metadata. Also, I don’t escape filenames yet.