Mastodawn

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.

Ballistics Swiss Knife — The Complete Reloading Toolkit

Free online ballistics calculator for handloaders. Estimate chamber pressure, model bullet trajectories, manage loading recipes, record chronograph measurements, and analyze shot groups.

Ballistics Swiss Knife