Apps similar to Dr. Geo include GeoGebra, which is free. Other options are GeoGebra Discovery, Winplot and CaRMetal. In total there are four Graphing Calculators like Dr. Geo for Windows, Linux, the web, Mac and Android.
GeoGebra is free and multi-platform dynamic mathematics software for learning and teaching. It has received several educational software awards in Europe and the USA.
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GeoGebra Discovery is an experimental version of GeoGebra. It contains some bleeding edge features of GeoGebra that are under heavy development and therefore not intended for every day use yet, so they are not included in the official GeoGebra version.
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"Winplot is a free graphing utility that was written by Richard Parris, a math instructor at Phillips Exeter Academy in Exeter, New Hampshire. Sadly Richard passed away in 2012. After Richard's death the program was still available for a number of years on the Exeter...
Dynamic geometry software based on René Grothmann's Compass and Ruler (CaR) software from 1989.
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