Copyscape Tops Plagiarism Checker Testing


Dr. Debora Weber-Wulff, a professor at the University of Applied Sciences in Berlin, has announced the results of her 2008 plagiarism software test (in German, translation) and, in something of an upset, Copyscape Premium takes the top spot.

Copyscape, which finished third in the previous testing, had its premium service rated first this year with its free service taking the third slot. Both version handily beat out popular academic plagiarism checkers such as Turnitin and SafeAssign.

Though the results may come as a shock to many in the academic community, especially those that pay for accounts at services targeted at universities, those that have followed Dr. Weber-Wulff’s work will likely not be surprised at all. Many will remember her work on exposing iPlagiarismCheck following the previous rounds of testing.

Nonetheless, her study offers a great deal for those interested in plagiarism to think about.


To conduct the tests, Dr. Weber-Wulff, along with her team, compiled 31 papers with known amounts of plagiarism and ran them through each of the applications and then rated their effectiveness on a scale of 0-3. They then rated their usability against a set of criteria, including Website of the company and cost transparency, the page layout and captions, workflow and navigation, on a similar scale. The points were then totaled up and ranked on the following scale.

  • Very good: 72-80
  • Good: 60-71
  • Satisfactory: 48-59
  • Sufficient: 40-47
  • Poor: 0-39

Also listed in the results were cancelled tests, meaning tests that could not be completed for some reason, and products that could not be easily compared against other plagiarism checkers, such as those designed to check medical databases.


In the end, none of the tests came away with a “Very Good” rating. However, Copyscape Premium did come very close, earning 70 out of a needed 72 points. Copyscape Premium earned the maximum number of points in a total of 23 out of the 31 tests.

Plagiarism Detector, another relative unknown, came in second, sandwiched between the two versions of Copyscape. Ephorus, last year’s top application, came in seventh this year, at the very bottom of the “Good” systems.

SafeAssign was number 8, coming in at the top of the “Satisfactory” systems and Turnitin was at the top of the “Adequate” list at 13.

However, several systems were not tested this year. Article Checker and CheckforPlagiarism were aborted, the first not fitting the criteria for a plagiarism checker and the latter not allowing free access for testing purposes.

Also, several commercial services were not slated for testing at all, including Attributor and iCopyright.


Though the results of the test certainly should give Copyscape’s developers a reason to cheer, there are several caveats, in addition to the services that were tested, that are worth mentioning.

First, since the test papers were in German, it remains to be seen how well the results would translate to English and other languages. Though I wouldn’t anticipate too much difference since the languages are similar, it could have a bearing on the results, especially with some of the more complex tools that may be language-specific.

Second, the usability tests were geared more toward teachers than they were Webmasters. The test is designed for the academic arena so this makes sense, but as Webmaster, it means that the usability results need to looked at in a slightly different light as our workflow needs are different.

Third, once again, it is important for Webmasters to realize that the results are geared for academic plagiarism, where it is important to trace one plagiarized work to its source, not one source to its many plagiarized copies. Though the search techniques are largely the same, many of the apps best geared at finding academic plagiarism don’t always detect all of the potential sources.

Finally, it is important to remember that the study itself is not an endorsement of any one plagiarism checking system nor is it a recommendation, it is only an analysis of how the various systems did on these specific tests, nothing more.


Though the results are interesting, what I glean most from this comparison is that, even though the standards were lowered for this round of tests, none of the services were able to achieve “Very Good”. This means that even the best plagiarism detection tools have flaws and need improvement.

Personally, I’ve never relied on just one means of detecting plagiarism, instead pulling my information from multiple sources. This study seems to reinforce that idea and further encourages me to back up any system I choose with alternates.

The simple fact is that no plagiarism system is going to be 100% effective and, as such, it makes sense to double up your net, especially since so many of the services are both free and easy to use.

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  1. Hi Jonathan

    I got very excited when I saw this post in my feed reader – I had not heard of CopyScape before (naturally, I assume since it is geared toward academic use it is probably marketed to that target audience so I imagine it would be less well-known outside of that particular strata)…….my first thought was “great! A new tool to help keep my work from being plagiarized!”…..very important since I'm knee-deep in creating a new site/blog geared to the writing community, with a lot of unique and proprietary content, including a couple of e-books…….so I was a little disappointed that it [CopyScape] sounds like it won't suit my needs…BUT I deeply appreciate your analysis so I didn't have to spend the time to figure that out on my own!

    I know you use a variety of very thorough methods to detect plagiarism, but are you aware of any special tool (like the software app you reviewed) that would actually help a webmaster who, as you point out, need to stay on top of detecting when/where their work has been copied?

    I realize that is a much more difficult task, and for the most part I've been relying on Google (searching for specific phrases to find out if any other pages are indexed with my content), but I wish there was some way to make this easier. Any ideas?

  2. Hi Trisha, Hi Jonathan,
    thanks for the kind words.

    The German system PlagAware was also in the “good” group, although it has an entirely different target group – webmasters.

    Jonathans advice is sound – use multiple systems. I am still a bit concerned about two of our test candidates. One would not answer emails for over a month, and is located in the Ukraine while pretending to be affiliated with an Australian university. The other had their lawyer threaten us with dire legal proceedings if we dared mention their names. Need I say that they came in last?

    Caveat emptor, and be aware that no system will find 100% of the plagiarisms. Even the “ideal” system, one that caught every plagiarism that any of the systems found, only had 77 out of a possible 93 points (before lowering the scale to 80).

  3. A few minor points.

    First, CopyScape is technically targeted at both crowds. It is advertised as a tool to help Webmasters check for plagiarisms of their content but the most common use of the pro feature, according to the developers, is to check other people's work for plagiarism, for example, paid blogging.

    So, in that regard, I would give Copyscape a try and see if it works for you, you can try the free version if you want. Also, take a look at Copy Alerts ( as they provide a similar service but send you email alerts when new copies are posted.

    Finally, keep your eye on companies like Attributor and iCopyright, mentioned above, as they are developing tools for high end publisher that will likely trickle down to individual bloggers.

    Hope that helps!

  4. I'm glad that you thought the advice to be sound. I've been using different systems long enough to know that no one is 100% and likely never will be.

    Sadly, it seems that this industry has attracted some less than honest players to the field. We both remember well the iPlagiarismCheck debacle and to have them bought out by another company using the name (though apparently the new company is at least somewhat more legit), is a clear warning sign of trouble.

    I'm not really sure why dishonest companies are attracted to this industry. It is far from easy money and the market, especially on the academic side, is relatively thin. There is a great deal of need for these services and money to be made, but it requires hard work and dedication, something a potential scammer would likely lack.

    Regardless, I'm glad for your tests, mainly because they expose the truly bad companies and highlight those that are at least working to get the best results possible. Thank you very much for all that you do.

  5. Hey guys,Can anyone help me whenever I put the URL of my new article in my blog..and I pass it trough copyscape I can see around8 to 10 results that show that have some words as the ones on my website. However when I open each link additionally to see what words were exactly copied there are no words…but just meta tags, or keywords or <title…html…> and stuff like this. it is full with all these. I write my content so I know is unique but still copyscape shows that it matches somebody's else wordpress theme meta tags or keywords …and it is weird. Is there anything I can do?Maybe I have not included some script in my wordpress or what?Please help me I do not want Google spiders to think I have similar content to somebody's else even if it is not words.thank you a lotGeri

  6. I guess using plagiarism detection software means trusting a service, because you should be very careful about giving out your work to someone else. I am a professor of English at the St. Michael's College and can share my experience of using an online plagiarism detection service. It is called <a href="” target=”_blank”> I am using it for over 10 months. I have tried them in many ways. For example, I have scanned one document in Nov., let's say. Than I forget about it for a couple of months and scan that same document in March. It does not find any relativity to other documents, so I can be 100% sure these guys are not keeping the databases. Everybody heard of scandals with turnitin and I don't want my students to participate in someone else's database gathering.

  7. Please help. My partner and I are working on a project which involves short (many times one-line) quotations from well known and not so well known writers, living and dead. They would include attributions to the authors. Would this project be likely to open ourselves to plagiarism charges?

  8. Hey Jonathan,I am really concern about what I blog about.My website has alot of traffic and I feel very concern about plagiarism.What is the first thing I need to do? I would hate to see my writings somewhere else that someone else did.What more can I do,can I place a badge on my website?

  9. Great tips here. It is all about hooking your reader and keeping them there. Unlike what they taught you in grade school you definitely want to front-load and lead with your best stuff. It is all writing to attract.

  10. Very interesting Information.
    Many people don’t know that copy content will not help their site. They kept on doing copy and paste.
    Find a time to write quality content and you will get the result within short period.


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