My graduate school doesn't offer TurnItIn facility.

All tools available online charge money.

How can a I check plagiarism free of cost before submitting my research paper?

  • 9
    Surely if you wrote the paper you already know whether you plagiarised any of it?
    – avid
    Commented Sep 3, 2020 at 6:59
  • @avid, some sentences need to be paraphrased.
    – user366312
    Commented Sep 3, 2020 at 7:03
  • 2
    @user366312 care to elaborate? Do you mean you wrote some sentences that you think are to similar to sentences in published papers? Or do you mean you copied them and want to check whether you can get them past some software?
    – Christian
    Commented Sep 3, 2020 at 7:07
  • 9
    @user366312 There is no need to paraphrase. If you need to copy a sentence from another paper, you need to do so with a citation and a very clear indication that it is copied (e.g., quotation marks and italic fonts). Hiding the copying by paraphrasing is plagiarism too. If the tool is detecting the sentences as similar by coincidence then it is not a problem. Nobody with a clean conscience would need to check their paper for plagiarism. Commented Sep 3, 2020 at 7:19
  • 2
    Then I do not see a problem. If you wrote them yourself they are probably something like "standard sentences". I fully agree with @TomvanderZanden - if you took them from another paper you have to cite them anyway.
    – Christian
    Commented Sep 3, 2020 at 7:53

2 Answers 2


Ask yourself a simple question: Did you plagiarise?

Assuming the answer is no, there's no need to check whether you plagiarised.

  • Some online tools are detecting some sentences which need to be paraphrased.
    – user366312
    Commented Sep 3, 2020 at 7:03
  • 2
    @user366312 Did you plagiarise?
    – user2768
    Commented Sep 3, 2020 at 7:09
  • no. absolutely not.
    – user366312
    Commented Sep 3, 2020 at 7:38
  • 6
    You have your answer, you should submit
    – user2768
    Commented Sep 3, 2020 at 7:46
  • 2
    @NateEldredge You'd merely learn that widely used checkers don't work, but we know that already
    – user2768
    Commented Sep 4, 2020 at 8:09

Perhaps these sources may help (I found them after doing some searching around), though to use them for free you may need to copy and paste your paper in chunks:

I think Grammarly also has a plagiarism detector, if I recall.

  • I've never tried a plagiarism detector before (nor have had anything I've written submitted to one, at least not that I know about), so on a whim I copied/pasted about 3 sentences from my highest voted Mathematics Stack Exchange (MSE) answer to your first link and got 100% plagiarised. I then did the same for about 3 sentences from one of my lowest voted MSE answers and got 0% plagiarised. In each case the selection I chose was something I felt was sufficiently uniquely phrased to not have been written by anyone else. I wonder if this means higher-traffic stuff is more likely found? Commented May 19 at 12:44
  • @Dave L Renfro I think that the more common a phrase is, the more likely it will be "caught" by the detector. I like to use it as something not too absolute; in that case I would use it just in case, but I wouldn't completely agree with 100% of what a detector would say Commented May 19 at 16:14
  • Strange, but now I'm getting 33% plagiarised. The phrase in question is: In 1977 Cliff Weil [8] published a proof that, in the space of derivatives with the sup norm, all but a first category set of such functions are discontinuous almost everywhere (in the sense of Lebesgue measure). When Weil's result is paired with the fact that derivatives (being Baire 1 functions) are continuous almost everywhere in the sense of Baire category, we get the following: From the middle of this MSE answer. FYI, Weil is my mathematical grandfather. Commented May 19 at 19:10
  • If it's catching things like "published a proof" and "space of derivatives" and "with the sup norm" and "all but a first category set" and "discontinuous almost everywhere" and "sense of Lebesgue measure", it may as well be set to catch the use of certain isolated words. Catching these phrases is like catching "Centers for Disease Control and Prevention" in a U.S. policy paper in epidemiology. Commented May 19 at 19:16

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