Description: GeoGebra is free and open-source dynamic mathematics software for all levels of education. It combines geometry, algebra, spreadsheets, graphing, statistics and calculus in one easy-to-use package. It can be used to teach math from elementary through university level.
Type: software
Pricing: Open Source
Description: Stack Overflow is a popular question and answer site for programmers. Users can ask coding questions and receive answers from a community of developers. The site has a reputation system to rate helpful responses.
Type: software
Pricing: Subscription