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.
Diffee Checker : Instant visual diffing with CSS blend modes!
Simply enter the sites you want to compare. Locally hosted addresses and files also work (so you can see ...
SPOF-O-Matic : Chrome extension for detecting and simulating frontend Single Points Of Failure. Detects likely third-party single points of failure as you browse and...
Sitespeed.io : Sitespeed.io is an open source tool that helps you analyze and optimize your website speed and performance based on performance best practices. It col...
Diagnostic.css is a stylesheet which allows the user to test for common errors in a page's markup.
