This is a free online math/scientific calculator similar to those from TI, Casio, HP and others. It supports functions for algebra and trigonometry. Enter a formula either by typing on the keyboard, pressing the buttons on the calculator by touch or with the mouse, or a mixture of both. See Operating instructions

Graphing calculator

This is not a graphing calculator, but see Graphical Function Explorer (GFE) which allows you to graph up to three functions at once with up to four independent variables controlled by sliders.