Ahrefs

Ahrefs is a professional SEO platform built by the company of the same name, used every day by marketers, content creators and site owners around the world. It runs on one of the largest and most accurate indexes of backlinks and keywords on the market, so it shows you how your site and your competitors really stand in search. The best part: the company offers Ahrefs Webmaster Tools (AWT) completely free for your own verified website — a quiet gem many people don't even know exists.

It works simply: enter a domain, a keyword or a competitor's page and Ahrefs returns an overview of links, organic traffic, keyword rankings and the site's technical health. It measures which terms a site ranks for, who links to it, how strong the backlink profile is and where a page has technical errors holding it back in search. Instead of guessing, you get numbers you can act on.