ffoodd/a11y.css: 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.
ygev/sketch-accessibility-assistant: Accessibility assistant for all your basic needs. Serves as a linter for compliant color contrast and type based on WCAG 2.1. Thanks to Ale Muñoz for his support and docs!
ColorTester - Software for test contrast ratio (WCAG 2.0 (JIS X 8341-3:2010) color contrast success criteria) between fore color and background color - アルファサード株式会社