The best free SEO tool depends on your specific needs and goals. However, some of the most popular and well-regarded free SEO tools include:

• Google Search Console: Google Search Console is a free tool from Google that provides you with insights into how your website is performing in search results. It can help you to identify and fix technical SEO issues, improve your website’s visibility in search results, and track your website’s performance over time.
• Google Analytics: Google Analytics is a free web analytics tool from Google that provides you with detailed insights into your website’s traffic and audience. It can help you to track your website’s performance, identify your most popular content, and understand how visitors are interacting with your website.
• Ahrefs Webmaster Tools: Ahrefs Webmaster Tools is a free tool from Ahrefs that provides you with insights into your website’s backlinks and organic traffic. It can help you to identify your most popular backlinks, track your website’s organic traffic, and identify any potential SEO issues.
• Screaming Frog SEO Spider: Screaming Frog SEO Spider is a free SEO tool that crawls your website and identifies technical SEO issues, such as broken links, duplicate content, and missing meta tags.
• Ubersuggest: Ubersuggest is a free keyword research tool that provides you with keyword suggestions and insights into search volume, competition, and CPC.