I have never seen so many tightly implemented and unique SEO tools in one place. The developer describes it as a tool he built for himself that has evolved over many years. The care and pride that has gone into this app is evident. It's powerful. It's mature. It's rock solid. And, from what I can tell, it undergoes constant evolution.

I don't, personally, even have an acute need for these tools (others do, but not me), but I am planning to keep my paid Appsumo version as a way to honor the coolness of the tool.