Crot Plagiarism

Using the crot plagiarism plugin
I am working on a Moodle 2.7 site, and wanted to add a plagiarism checker in. There are some really good commercial ones available, but I wanted to find a free version to show the client. After checking out all the free versions, none of which worked in Moodle 2.7, I settled on using the crot plugin.

The plugin was developed by Sergey Butakov, but sadly did not work in Moodle 2.7 (

Fortunately it was not too difficult to tweak the code and make it work in Moodle 2.7. Once installed and working, I accessed the plugin and enabled it. All the other options I left at their default settings.


There are some things I could not fix. Because of a change to the Bing API, a web search is not possible. For my demo that was fine, as long as I could compare uploaded files and inline text in the assignments.

Once you have the crot plugin installed, head over to the assignment activity and enable it. As mentioned, there is no way to compare the content with content on the internet, so you don’t need to turn this option on.

If the plugin is working correctly a message will be displayed to the students telling them that the content will be subject to a plagiarism scan. You can see that message in the image below in the top left corner.


If you are going to be testing the plugin, make sure you run the cron job after every activity. The image below shows the crot plugin activity in the cron.


I created some data using student roles. The image below shows the result once the cron had run and a plagiarism check had been performed.


Clicking on the 100% hyperlink will load a table showing the percentage similarity. Click once more on the 100% hyperlink to view a comparison of the content.



Even if you reorder the content, crot still manages to find and highlight the similarities in the text.


The same happens when uploading a file. In my tests I only used .txt files and the plugin managed to scan and report back on them without any problems.

As mentioned previously, this is an update to the plugin Sergey Butakov built, so all thanks to him for all the hard work he did.

If anyone would like to play around the the plugin, you can download it here: link

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