The guys over at metafever have an excellent collection of almost 80 (!) free SEO online tools, this is probably the best list of tools of that kind in one place – and it’s 100% free.
The collection conists of any kind of SEO tools, starting from backlink checkers, keyword and keyword density checkers, header checkers and what not. Its absolutely excellent. Thanks to metafever from warrior forum to provide such a list and easily accessible free tols! Check them out here.