1. Colour contrast analyser

    The Colour contrast analyser is a simple but effective free Windows program to calculate the contrast between two colors. With it you can check if a color combination for displaying text provides sufficient contrast when viewed by someone having color deficits, or viewed on a black and white screen.

    There are other tools online that also can do this check, but most of them need two RGB color values. That's also possible with this program, but it comes with a much easier color picker that magnifies a part of the screen to pick the colors you want to check.

    The calculation used is based on an algorithm suggested by the W3C.