Dr. Link Check - Broken link checker with malware and parked domain detection
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
LinkChecker - LinkChecker is a free, GPL licensed website validator.
Ahrefs - Ahrefs is a toolset for SEO and marketing. We have tools for backlink research, organic traffic research, keyword research, content marketing & more. Give Ahrefs a try!