Integrity - Feature comparison of link checkers for Mac: Integrity, Integrity Plus and Scrutiny
Total Validator - Total Validator can check your website to help ensure that it is accessible, uses valid HTML and CSS, has no broken links, and is free from spelling mistakes.
Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
W3C Markup Validation Service - Validates HTML markup of web pages, one at a time.
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...
Rocket Validator - Site-wide Accessibility and HTML validation made easy. With a single click, Rocket Validator will check thousands of web pages on your site for Accessibility and HTML conformance, producing a detailed, actionable report on seconds.