Website Grader - Grade your website's strengths and weaknesses in seconds.
Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
Smaller - Make your websites load faster
Scrutiny - Scrutiny for Mac helps you manage and improve any number of websites. Link check, search, full website spell check, XML sitemap generator, SEO audit
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
LinkChecker - LinkChecker is a free, GPL licensed website validator.