C.a.R. stands for 'compass and ruler'; and it is an open source geometry application. This program features a context-sensitive multilingual GUI with a nice layout and tons of tools, which can help us to work with geometrical constructions, including animated and three-dimensional one. We can draw/edit lines, points, circles, perpendicular lines, parallel lines, midpoints, functions, curves, angles, macros, breakpoints, set assignments, add text, use the color palette and grid, paint with our mouse, set macroparameter and definitions, set the object color and thickness, replay the constructions, choose the beginner mode, export to HTML, export templates, and much more. The sample section allows us to load and work with already made applications, templates, autodemos, macros, etc. This comprehensive program may help students, teachers, designers, engineers, and so on. A discussion forum offers information and support. It is possible to contribute to the further development of this free utility, report bugs, translate to other languages, etc. This program needs Java to run, and it supports all platforms.