There’s an early alpha version of FredCropper out now.
It’s still lacking a bunch of planned features, the interface isn’t finished (note the bottom of the modal), and it needs a lot of testing.
As it’s alpha, don’t use it on a production site.
It requires Fred to also be installed of course, and it doesn’t support Internet Explorer.
You can install it via the MODX package manager and please report any issues at the github page:
Hope it’s found to be useful!