LinkChecker - LinkChecker is a free, GPL licensed website validator.
Checkbot - Checkbot will boost the SEO, speed and security of your site by checking you're following 50+ web best practices. Browser extension with free and paid plans.
Pulno - SEO Audit and Website Analysis. Pull up your SEO.
Dead Link Checker - Check for broken links on any website
Dr. Link Check - Broken link checker with malware and parked domain detection
Meta Forensics - Meta Forensics is a website architecture, internal link and SEO analysis tool that helps identify...