The SEO crawler that won't stay quiet about your site's problems.
Paste your page and the pages ranking for your subject. Every term is weighed across all of them, and yours is measured against their average.
It reads your page and the ones you name, counts the words and phrases on each, and weighs every term with TF*IDF: how much a page uses it, corrected for how many pages in the set use it. Then it averages the competitors and measures you against that average.
Every term carries two bars on the same scale: yours and the others' average. Missing is a term they use and you do not. Thin, one you mention far below the average. Overused, one you repeat far more than any of them, which is what keyword stuffing looks like from the outside.
The list of terms only on your page is what you say and none of them do. Sometimes the brand, sometimes what makes you different, and sometimes the sign that the page is about something else.
It does not find out who ranks. It compares the pages you give it. Knowing who is in the top ten for a search needs a results API, which is the part that costs money. Paste the URLs of the results you want to beat.
Filler words are removed with the list for the language your page declares. A page that declares none has none removed, and this page says so.