Dr. Link Check - Broken link checker with malware and parked domain detection
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.
LinkChecker - LinkChecker is a free, GPL licensed website validator.
Backlink Tool - A backlink tool to index your links quickly and freely.
SuperSend.io - Automate Cold Outreach Across Email, Linkedin and Twitter.
SEMScoop - Find and analyze easy to rank long-tail keywords with free SEMScoop Keyword Difficulty Tool, Start using them for SEO, PPC, content creation and all your marketing activities