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.
Polypane - The browser for ambitious web developers that want to 5× their quality and efficiency.
Colorific - Colorific Hair Color Salons give you amazing color at an affordable price.
CSS Scan - Instantly check or copy computed CSS from any element for only ~95$
HTML Validator - HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla.
Wireframe for Figma - Lightning fast wireframing on figma (500+ elements)