Whenever I have some free time on my hands, I check StackExchange answers for plagiarism. I am not referring to cross-SE plagiarism, I am looking to check answers posted on SE that have their content plagiarized from other Internet sites.

I initially used to do this the lame way (paste into google, put double quotes, rinse repeat for different sentences). Today I googled "plagiarism checker online" and there's dozens of such software all willing to do this for free! Some do require an account sign-up but that's a non-issue (Guerrilamail ;))

Since I have not used any of those, I am not sure how effective they are. I just ran a check through two of the first hits - SmallSEOTools and QueText. The former wasn't even able to identify the original SE answer from which I copied the text, while the latter correctly did. Grammarly requires a paid plan, however, I am looking for free ones only.

So, I am looking for the most effective free online plagiarism checker, hopefully optimized for StackExchange answers (average length: 1200 characters)

To properly define plagiarism, specifically in the context of StackExchange, it would be when a user posts content - copied from an external resource (different SE answer/off-site resource) - with no attribution (link, textual citation, any sane indication) to the original source whatsoever. For an example, answer A is an example of plagiarism (no visible attribution), while answer B is not (clear attribution).

  • Just out of curiosity, why is this of interest to you?
    – Seamus
    Commented Jun 25, 2018 at 20:42
  • 2
    @Seamus I have some free time these days, so I am trying to put it to productive use :) Commented Jun 26, 2018 at 0:32
  • Well that's fine. I asked because I suspect that under some definition of plagiarism, there's a tremendous amount of it. Consider an entry on the command line; to use a ridiculous example, ls -la, or sudo apt-get upgrade. I imagine you'll find huge numbers of "repeats" of this sort of thing; even with commands that have literally many thousands or even millions of permutations and combinations of all the options. Point is that a lot of posts in the technical forums would seem to follow a "structured subset" of the language, and I'd only guess that those aren't considered plagiarism at all.
    – Seamus
    Commented Jun 26, 2018 at 12:27

1 Answer 1


I don't think there is a specially curated tool available on the Internet. Google site: search can be a way to find similar content available on the website. e.g: site:stackexchange.com + "your content here".

Free software tools are not much effective as they are only capable to detect direct plagiarism, but, are unable to detect the variations. Not even the spatial variations. You can use "diff" Unix utility after you identified the correct URL to check the percentage of similarity. Or you can also check Turnitin or other alternatives. Some give a free trial if you are interested.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.