Web Experience Toolkit (WET): Open source code library for building innovative websites that are accessible, usable, interoperable, mobile-friendly and multilingual. This collaborative open source project is led by the Government of Canada.
The Colour Contrast Analyser (CCA) helps you determine the legibility of text and the contrast of visual elements, such as graphical controls and visual indicators.
This CSS file intends to warn developers about possible risks and mistakes that exist in HTML code. It can also be used to roughly evaluate a site's quality by simply including it as an external stylesheet.