Free interactive geometry software
DrGeo
GNU Dr. Geo is interactive geometry software that allows its users to design & manipulate interactive geometric sketches. It is free software (source code, translations, icons and installer are released under GNU GPL license), created by Hilaire Fernandes, it is part of the GNU project.It runs over a Morphic graphic system (which means that it runs on Linux, Mac OS, Windows, Android). Current version of Dr. Geo is also called Dr. Geo II. Historically Dr. Geo was developed in C++ and Dr. Geo II is a complete rewrite using Pharo that happened in 2005. This article refers to the most recent version. (Wikipedia).
