I write this post mostly to help people that rewrite or spun content for their backlinks and have limited copyscape access. Because most of the content spinner tools create articles from paras from different articles and very regular the final result do not make sence, but if we can spin/rewrite single article wich will pass copyscape will be great correct!? I think the best plagiarism checker tool is copyscape. I think it is the tool that works very similar to search engine bots and even I think it works in the same way. I thought a lot for this and I consider, that this is the only algoritm to find if the content is unique in deep. Why? After I tried a lot of plagiarism checker tools (have tons free), I noticed that most of them just checking sentences or parts from content on g00gle search. Than they do simple math: numberUniqueSentences/totalNumberSentence*100 In most cases when such tools return 90%+ uniquiness, the content passed copyscape. But, sometimes not! This is the reason in my head come the questions: How copyscape algoritm catching the dupe content? When they do it so fast (copyscape and search engines) it must be some simple thing, correct? So to answer these questions I tryed to make a programme, that will try to find the original source from spun content (like copyscape do). And consider to only way to do this is in 3 modules: 1. split the content and chek each part of content against g00gle search (,;:!?. are parts' separators) 2. if some part return results compire words popularity and words count between the checked content and the content of returned URL's content. If popular words and number of words are near the same, than most possibly the content is spun/rewritten and go to module 3. 3. calculate how many words exact matches and if the % of the mached words is higher than e.g. 20%, mark as duplicate. I don't thing, there have other way to check fast. So how to be sure search engine algorithms and copyscape will not understand if we spin/rewrite an article (well copyscape at least)? Just be sure each part of the content returns no results from g00gle search. You can use some plagiarism checker from the download section on the forum. FAQ Q. Why it will pass copyscape? A. Copyscape will have nothing to use to move on the next steps from the algorithms. Q. Well, ofcourse if each part of the article returns no results from G00gle it is unique. Then why you wrote this? A. Because most common practice is to rewrite few sentences if copyscape returns dupe or even to skip/remove the paragraph. Now if you understand my post, with only free tools and very little rewrite - only the part of the article wich returns results, you can produce hq copyscape passed articles.