Spin Rewriter 5.0 technology was a previous edition that allowed their clients to use the basic article rewriting system.  Their newer versions over the years have just kept getting better and better.   The new Spin Rewriter 9.0 technology gives you the option of assigning variables to your content.  Their software is dead easy to use.  In just three steps you can have up to 50 uniquely spun articles.
This excellent article rewriter tool will thoroughly scan your entire content, looking for the words that it can replace with a synonym. All the words that it replaces with a substitute will be highlighted in the bold and colorful text. By clicking on any of the highlighted words or phrases, you can see the original word, suggestions or add your own word. Also, you can click on the original word to revert or click on any other word to replace.
Imo it is not possible for google to detect properly spun content, it is not worth computing power it requires. They can do this using ngrams for example, but it is uses a lot of queries. And for example article spinner I coded beats this algo, so google cant detect that the content is spun. Manual spinning is also good but it takes more than 30 minutes per article.