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.
I've ranked websites in the past with spun content, and now they are still on #1 position of google. First year (2014) google found me because my spun was really bad, many paragraphs were just copied and my position drop from #2 to around #20 after a panda update. Later I cleaned all my text with better spun (I didn't buy any article!), my ranking went up again, and with more backlinks I reached #1 and it is still there