SpiroJ is a simple generator of hypotrochoids and similar roulettes. The basic principle is rolling one circle on another circle - similar to the classic Spirograph toy, but more flexible. It can export drawing to SVG, EPS and AI formats.
Created by František Grebeníček. Originally released on sourceforge in 2014 and migrated to GitHub in 2023. It is not under active development, but shared here for posterity. License: Public Domain.
