Desmos

In addition to graphing both equations and inequalities, it also features lists, plots, regressions, interactive variables, graph restriction, simultaneous graphing, piecewise function graphing, polar function graphing, two types of graphing grids — among other computational features commonly found in a programmable calculator. It can also be used in several different languages. Users can create accounts and save the graphs and plots that they have created to them. A permalink can then be generated which allow users to share their graphs and elect to be considered for staff picks. The tool comes pre-programmed with 35 different example graphs for the purpose of teaching new users about the tool and the mathematics involved.