tota11y - An accessibility visualization toolkit from Khan Academy

Workona - A better way to work in the browser.

Nibbler - Free tool for testing how good your website is, and what you can do to improve it. Check accessibility, SEO, social media, compliance and more.

OneTab - Whenever you find yourself with too many tabs, click the OneTab icon to convert all of your tabs into a list. When you need to access the tabs again, you can either restore them individually or all at once.

Page Speaker - Modern web accessibility tools for agencies & webmasters

Tabbie - The missing tab manager for Chrome