Netpeak Spider - A desktop tool for fast and comprehensive technical audit of the entire website.
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.
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.
Backlink Tool - A backlink tool to index your links quickly and freely.
SEO Crawler - A web-based crawler with real-time crawl feedback.
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