This table contains the results of the October 26, 2022 exploration of accuracy of free plagiarism checkers online. Commentary follows.
On October 26, 2022 a test to determine the accuracy of free plagiarism checkers in Google was completed by Golemon Library. A key word search for 'free plagiarism checker' was done in Google and all of the options on the first page of results were opened. The same batch of text was processed through each to decide which was the best. The text had three plagiarized statements as control. Additionally, the same document was processed through Canvas’ Turn-it-in to get a feel for what the free versions were finding compared to what the official version would find.
There were a lot of similarities, but no two sites were identical. All had strengths and weaknesses. Ultimately, Turn-it-in was the strongest because was able to upload unlimited size document, found all the issues, and created an easy to read report.
Considering that finding acts of plagiarism is the most important factor, the best free version out there is Check-plagiarism.com. Many found all three of the control items, but there was also an additional paraphrased sentence. This was the only free checker that found it. There were two sentences that were so common they could be considered unplagiarizable, but they were found in all but one free version so it is hard to exclude this one because of that. If a professor wants to charge you with plagiarism for ‘a picture is worth a thousand words’ you have a good case for a complaint.
Now, let’s look at the numbers. Eleven different features of the free checkers we evaluated and each assigned a number from 0 to 1, in .25 increments. While Check-plagiarism.com was the clear winner in plagiarism detection, when all other features were looked at, prepostseo.com was the winner by a wide margin, coming in with 8.5 points. Its selling point is that it was the one that did not find a common phrase as plagiarized. It was also one of the fastest processing. Its reason for winning was that it got points of some kind in every category, so it covers all the bases.
For the losers, there are three easy selections. Chegg, easybib, and quetext were not free, even though they advertised as such. Chegg and easybib required registration for a free three day trial, which of course, converts to a subscription when the trial period ends. Three days might get a student through finals, but not four years. Quetext required registration for a free account and all seemed to go smoothly until you actually hit submit on the text. Then you get an announcement that you have used all your free attempts.
For the actual free checkers, papersowl.com was the big loser. It found no plagiarism issues. Even though it had no word limit, it doesn’t matter if it can’t find the control items.
Raw results can be found below and the spreadsheet of information is at the top of this page. In the end, for free plagiarism checkers, the recommendation is Check-plagiarism.com. There are some great features in the others, but the reason for being here is to check plagiarism and this did that best.