Ballistics Swiss Knife — The Complete Reloading Toolkit
www.bskcalc.com
Free online ballistics calculator for handloaders. Estimate chamber pressure, model bullet trajectories, manage loading recipes, record chronograph measurements, and analyze shot groups.

The author announced it in this reddit thread.

I set up a few loads in it and it seems to work fine. Registration required, probably because it allows you to save/edit/dupe loads.