SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Dr. Link Check - Broken link checker with malware and parked domain detection
SEOmator - SEO website analysis & audit tool
LinkChecker - LinkChecker is a free, GPL licensed website validator.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks