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.
Dr. Link Check - Broken link checker with malware and parked domain detection
Colorific - Colorific Hair Color Salons give you amazing color at an affordable price.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
HTML Validator - HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla.
LinkChecker - LinkChecker is a free, GPL licensed website validator.