LinkChecker - LinkChecker is a free, GPL licensed website validator.
Ahrefs Backlink Checker - With the world's biggest index of live backlinks (over 15 trillion), Ahrefs Backlink Checker will show you the most complete backlink profile for any website.
Dead Link Checker - Check for broken links on any website
SmallSEOTools - Do you need effective SEO tools which are 100% free? Check out our SmallSEOtools.com for checking and removing plagiarism, backlinks, tracking keyword positions, and more.
Pulno - SEO Audit and Website Analysis. Pull up your SEO.
SmallSEOTools Keyword Rank Checker - Use our free keyword rank checker tool to track keywords position for website. Enter Keywords and Url and see keyword position checker report instantly.