Meta Tags - Meta Tags is a tool to debug and generate meta tag code for any website.
Serpstat - Search analytics, Rank tracking, Backlink analysis and Site Audit tool.
Screpy - Screpy is a web analysis tool that can analyze all pages of your websites in one dashboard and monitor them with your team. It's powered by Lighthouse and it also includes some different analysis tools (SEO, SERP, W3C, Uptime, etc).
Ubersuggest - Want more traffic? Ubersuggest shows you how to win the game of SEO. Just type in a domain or a keyword to get started.
Rank Math SEO - A FREE powerful and lightweight SEO plugin for WordPress
Curatedseotools.com - Curated directory of the best SEO tools.