Ahrefs - Ahrefs is a toolset for SEO and marketing. We have tools for backlink research, organic traffic research, keyword research, content marketing & more. Give Ahrefs a try!
Xenu's Link Sleuth - Xenus Link Sleuth checks Web sites for broken links.
Google Search Console - Google Webmaster Tools provides you with detailed reports about your pages' visibility on...
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
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
LinkChecker - LinkChecker is a free, GPL licensed website validator.