Some of the best free SEO tools include Ahrefs, Google's Structured Data Docs, Google's Rich Search Results Test, Google Search Console, SEO Stuff's Free Keyword Generator, and AnswerThePublic. These tools cover various aspects of SEO like keyword research, on-page optimization, backlink analysis, and content ideation.

Ahrefs offers a generous free tier that allows you to view your domain ranking, track backlinks, view organic keywords, analyze page and backlink health, and check out competitors. Once you sign up and connect your domain, you'll receive weekly reports on your SEO progress.

Google's Structured Data Docs explain what kind of structured data you need to provide to get certain types of search results. This includes breadcrumbs, articles, carousels, courses, reviews, FAQs, products, recipes, and more.

You can use Google's Rich Search Results Test to view your search results as Google sees them and to spot potential errors or areas for improvement in your structured data and JSON-LD implementations.

Google Search Console allows you to see your site's Google traffic and helps Google index your pages. You can view the number of search impressions, search clicks, keywords used, track links to your pages, check core web vitals, and crawl stats. You can also manually request crawling of certain pages and upload sitemaps.

SEO Stuff's Free Keyword Generator provides up to 20 keyword suggestions for every keyword you enter. For each keyword, you can find out how difficult it is to rank and what the average search volume is. It supports multiple keyword languages.

AnswerThePublic is a tool for generating content ideas based on major Google searches containing your keyword. For example, if you type in 'ranking,' you can get suggestions for 'ranking of Taylor Swift songs,' 'ranking list,' 'ranking of US presidents,' and more. It has a free tier that allows three searches per day.