Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.

GTmetrix - GTmetrix is a free tool that analyzes your page's speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers actionable recommendations on how to fix them.

Ahrefs - Ahrefs is a toolset for SEO and marketing. We have tools for backlink research, organic traffic research, keyword research, content marketing & more. Give Ahrefs a try!

PageSpeed Insights - PageSpeed is addon for ...

Serpstat - Search analytics, Rank tracking, Backlink analysis and Site Audit tool.

CheckPageSpeed.com - Website Speed and Performance Analyzer