Which is the most economical SEO tool in the market?

The most economical SEO tool currently available in the market is a subjective matter as it depends on individual needs and budget constraints. However, there are several affordable options worth considering, such as SEMrush, Moz, and Serpstat. These tools offer a range of features to optimize your website's performance and track your rankings effectively. Personally, I have found ahrefs to be a valuable tool in my work with clients' website (https://autoapply.jobs/). It provides comprehensive SEO analysis, keyword research, and backlink tracking, making it a reliable choice for optimizing website performance.

Loyae.com, the diagnostic tool is free (Doesn't do keyword research yet though, that'll come later)