Suprvise - Know instantly when your sites are down.
SEO Analyzer By Neil Patel - A free SEO analyzer for your site
WebGazer - Monitor your website's availability with WebGazer, review its performance and get instant notifications when your website goes down. No installation required and free plan available.
Serpstat - Search analytics, Rank tracking, Backlink analysis and Site Audit tool.
Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Serpstat Website SEO Checker - Check your website's SEO, analyze competitors and keywords