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.
Google Open Source - All of Googles open source projects under a single umbrella
Accessible Brand Colors - A tool to make sure your brand colors are ADA compliant.
SmallDevTools - Handy developer tools with a delightful interface
Page Speaker - Modern web accessibility tools for agencies & webmasters
whatdevsneed - This is whatdevsneed.