C.a.R.

C.a.R.– Compass and Ruler (also known as Z.u.L., which stands for the German "Zirkel und Lineal") — is a free and open source interactive geometry app that can do geometrical constructions in Euclidean and non-Euclidean geometry. The software is Java based. The author is René Grothmann of the Catholic University of Eichstätt-Ingolstadt. It is licensed under the terms of the GNU General Public License (GPL).

Assignments
Assignments make possible to create Java applets, for a construction exercises. These applets can be used from the command line using the AppletViewer. (Previously, they could be run in a browser, but Java support in browsers has been disabled in recent years.)