It is a module in a software that used to be named Keyword Thief. This product started as a spider that extracted keywords from the top-ranked sites in Google.
In a second stage, it incorporated 3 modules:
– Metatag Thief, which does the same as Keyword Thief, but for all metatags
– Algo Cracker, an analyzer of keyword density in different parts of the Google top-ranked websites. It uses ranges (clusters) of pages, to allow averaging and comparing
– Metatag Analyzer, a spider that enters a single site, and checks the contents of all metatags.
This products are now sold together, but can later evolve separately.
See http://keywordthief.com.ar for details and free download.