Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
Smaller - Make your websites load faster
Dead Link Checker - Check for broken links on any website
Website Grader - Grade your website's strengths and weaknesses in seconds.
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!
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.