Starting with that lazy definition What is SEO?-

SEO stands for Search Engine Optimization, which is the practice of increasing the quantity and quality of traffic to your website through organic search engine results.

All list of SEO tool,

1. Matomo

Matomo, is a free and open source web analytics application developed by a team of international developers, that runs on a PHP/MySQL webserver. It tracks online visits to one or more websites and displays reports on these visits for analysis. It's a Google Analytics Alternative.

-> matomo.org

2. Keyword Surfer (Extension)

Keyword Surfer is the fastest way to reveal search data and perform keyword research in Google Search. It’s 100% free. Forever.

Once you type your target phrase and press enter, you’ll uncover search volumes, keywords suggestions, related terms, visibility metrics, and on-page data.

Based on that you can find the best keywords, determine their difficulty and plan your content. No need to purchase any expensive tools — Keyword Surfer

For every new search you conduct in Google, you’ll get invaluable data for content and SEO strategy:

• Search volume for your primary keyword
• Similar keywords with their volumes and similarity score
• Estimated traffic for a domain of each top-ranking page
• Related searches with their volumes
• Word count for top-ranking pages
• Number of exact keywords used on top-ranking pages
• Cost per click (CPC) for your primary keyword

For more information go to docs.surferseo.com/keyword-surfer-extension

Chrome -> chrome.google.com/webstore/detail/keyword-s..

3. SEORCH

It is a free SEO tool and offers you a detailed overview of the technical SEO implementation of your site. You get a complete evaluation of your HTML structure and a direct rating by green check marks or red crosses.

SEORCH ->seorch.eu