SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
SEOmator - SEO website analysis & audit tool
Whatsmyserp - Powerful Rank & Serp Tracking. Completely Free.
Lumar - (Previously DeepCrawl) Hosted SEO spider to analyze and find problems with websites.
Seolyzer - Seolyzer is the ultimate SEO tool that provides you with all the information you need to improve your website’s health and performance.
SEOquake - SEOquake provides a browser extension to conduct on-page SEO audit.