SiteAuditTool.com - Generate Website Audit Reports
LinkChecker - LinkChecker is a free, GPL licensed website validator.
SEO PowerSuite - Get all SEO tools in one pack - download free edition of SEO PowerSuite and get top 10 rankings for your site on Google and other search engines!
DRKSpiderJava - DRKSpider is an open source website crawler (sitemap generator) and link checker. Features:
SiteCheckerTool.com - Website Analytics & Tools
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.