Netpeak Spider - A desktop tool for fast and comprehensive technical audit of the entire website.
Dead Link Checker - Check for broken links on any website
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.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
SEO Crawler - A web-based crawler with real-time crawl feedback.
LinkChecker - LinkChecker is a free, GPL licensed website validator.