This is absolutely useless. It claims it rewrites English sentences, but it just offers words alternatives, which is only nouns. Also, most of those suggested alternatives are unable to use. If you see their maker's home page, Whitehat Box, you can see numerous people request the refund. It's far from western progressive software like Grammarly or sketch engine. They stole my money with the diceiptive advertisement.
There are some 'free' article spinners out there that require you to enter your text with properly formatted 'spintax' in order to create the end result. But how you need a totally separate tool to create this machine formatted text, so how is this really useful to you? Spinbot does all thinking for you, from taking in the context of every phrase to creating additional textual content that is as readable and meaningful as the text you originally entered.