Nibbler - Free tool for testing how good your website is, and what you can do to improve it. Check accessibility, SEO, social media, compliance and more.
Integrity - Feature comparison of link checkers for Mac: Integrity, Integrity Plus and Scrutiny
FreePlagiarismChecker - Plagiarism scanner that detects plagiarism in your text.
Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
CSS Scan - Instantly check or copy computed CSS from any element for only ~95$
Screaming Frog SEO Spider - The Screaming Frog SEO Spider is a small desktop program (PC or Mac) which crawls websites’ links...