webhint : webhint is a linting tool that will help you with your site's accessibility, speed, security and more, by checking your code for best practices and co...
Pa11y : Monitor the accessibility of your websites with pa11y-dashboard, and protect against accessibility errors creeping into your codebase.
tota11y : an accessibility visualization toolkit that aims to reduce the friction of a11y testing
WebScarab : WebScarab is a framework for analysing applications that communicate using the HTTP and HTTPS protocols.
WebPagetest : Run a free website speed test from multiple locations around the globe using real browsers (IE and Chrome) and at real consumer connection speeds.
Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup.
