SEO Analyzer By Neil Patel - A free SEO analyzer for your site
Curatedseotools.com - Curated directory of the best SEO tools.
Serpstat Website SEO Checker - Check your website's SEO, analyze competitors and keywords
SEO Marketing Hub - Learn SEO for free
Serpstat - Search analytics, Rank tracking, Backlink analysis and Site Audit tool.
SEO Minion - Chrome extension & Firefox add-on to help you with SEO