View websites through the eyes of the colorblind.
Simulate 4 different kinds of color blindness in two different degrees (e.g. protanopia and protanomaly) each.
There are two ways to use it: by default, it will display a popup with buttons to choose the kind of color blindness to simulate. If you only ever use one, you can go to the options and set it so that pressing the button will simulate a kind you choose (saving you some clicks in the long run).