PBN Hunter is a web based tool that allows Search Engine Optimisation specialists to see if their competitors are ranking using a hidden private blog network.
When we say hidden we mean blocking all backlink crawlers such a ahrefs, moz and majestic SEO.
Blackhat webmasters block these backlink crawlers so their competitors can't find their private blog networks.
If these private blog networks were exposed they could be reported to the Google spam team.
Although the main use of this tool should be to know how a competitor is truly ranking before you enter a niche.