Site Valet : Web Tools for Quality, Accessibility, Standards Compliance.
Diagnostic.css : Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup.
Also : https://github.com/karlgroves/diagnostic.css
Lighthouse : Lighthouse is an open-source, automated tool for improving the quality of web pages. You can run it against any web page, public or requiring authenti...
Pa11y : Monitor the accessibility of your websites with pa11y-dashboard, and protect against accessibility errors creeping into your codebase.
Screenfly : Test Your Website at Different Screen Resolutions
The mobiReady testing tool evaluates mobile-readiness using industry best practices & standards.
