LensSim is fully functioning and I would welcome others trying it out.
I wrote it for those that wish to understand their lens, based on knowing the focal length, the aperture, the focus distance from the sensor, the minimum focus distance, the magnification at the minimum focus and the pupil magnification. All fairly easy to obtain.
LensSim then allows you to see how your lens front and rear principal planes and entrance and exit pupils move as you focus.
Remembering that the entrance pupil is the location of the pano pivot point, and that towards the macro end of the lens, the pupil mag effects depth of field. Plus see lens breathing.
Finally, don’t forget my DOFIS depth of field script, which allows you to capture perfect focus brackets and, if you wish, exposure brackets as well.