Whether searching for a product or determining what others are buying, entering a keyword is the first step. Select the ebay longtail keywords from the list that are most relevant and download them. By typing the results into Ebay, you will quickly see if there is a demand for your product. As a buyer you will get the most relevant products to your search.
Ahrefs is incredibly comprehensive and straight forward. From keyword discovery to site audits I use ahrefs for all my SEO needs. It's the first SEO program I was introduced to when starting me SEM management career and has proven to be the best time and time again. I've used their competitors liker moz, SEM rush, and a couple other services- none of which have come close to stacking up.
Ahrefs make use of two link updates in your website - the Fresh Index and the Live Index. Fresh Index which updates at a longer time frame. It shows the dead links on your website, giving you the chance to change or reclaim the dead link. The Live Index, on the other hand, makes link updates every 15-30 minutes. This provides you with the chance to see regular link updates on your website.