RobinGupta Bulk Domain Authority Checker - Free tool to bulk check domain authority, Page Authority, Spam score & IP Address.
Check My Links - Highlights broken links on page
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.
Panguin Tool by Barracuda Digital - See your website's Google organic visit data overlaid with Google's major algorithm updates and changes to easily identify the impact on your website. Technology by Barracuda Digital.
Checkbot - Checkbot will boost the SEO, speed and security of your site by checking you're following 50+ web best practices. Browser extension with free and paid plans.
SEOmator - SEO website analysis & audit tool