Plagiarism: Crot Plagiarism Checker

Maintained by Picture of Sergey ButakovSergey Butakov
This FREE plugin is aimed at digital plagiarism detection: it uncovers assignments copied from peers at the same institution. The module is language independent. Maintainer: Sergey Butakov More information:
43 sites
11 fans
Current versions available: 2

Block is based on document fingerprinting technologies for pair-wise document comparison.

Please note that as of August 01, 2012 the block does not perform global / Internet search due to monetization of Bing search engine API.


A distinctive feature of this plug-in is that all local checkups are happening on your Moodle server without sending any documents outside. Thus, in contrast to other available solutions, the plug-in does not impose any issues related to student intellectual property protection. 


This module is the successor of  Crot for Moodle block: This version is tailored for the plagiarism API in Moodle 2.x.

This is standalone module that doesn't require a connection to the external plagiarism detection service. 

Maintainers: Sergey Butakov, Svetlana Kim

More information:


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Picture of Sergey Butakov
Sergey Butakov (Lead maintainer)
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  • Picture of Daryle Niedermayer
    Wed, Dec 21, 2011, 7:34 AM
    Have the same error. Crot worked fine on Moodle 2.0.5+, but after upgrading to Moodle 2.2, I get the following error:
    Table "plagiarism_crot_config" does not exist

    More information about this error
    Stack trace:

    line 505 of /lib/dml/moodle_database.php: dml_exception thrown
    line 1077 of /lib/dml/moodle_database.php: call to moodle_database->where_clause()
    line 1169 of /lib/dml/moodle_database.php: call to moodle_database->get_records()
    line 118 of /plagiarism/crot/lib.php: call to moodle_database->get_records_menu()
    line 116 of /lib/plagiarismlib.php: call to plagiarism_plugin_crot->get_form_elements_module()
    line 1036 of /mod/assignment/type/upload/assignment.class.php: call to plagiarism_get_form_elements_module()
    line 72 of /mod/assignment/mod_form.php: call to assignment_upload->setup_elements()
    line 154 of /lib/formslib.php: call to mod_assignment_mod_form->definition()
    line 71 of /course/moodleform_mod.php: call to moodleform->moodleform()
    line 256 of /course/modedit.php: call to moodleform_mod->moodleform_mod()
  • Picture of Sergey Butakov
    Thu, Dec 29, 2011, 12:33 PM
    Please refer to Crot forum on this site. I posted a temporary solution there.
  • Picture of José Eduardo Martins
    Wed, Apr 18, 2012, 12:27 AM

    Could you point me where is the Crot forum. I have the same problem with crot and moodle 2.2.

  • Picture of Sergey Butakov
    Fri, Apr 20, 2012, 8:27 PM
  • Picture of Sergey Butakov
    Mon, Sep 24, 2012, 9:12 PM
    No it doesn't work with 2.3 at the moment. Please read forum for the details and questions.
  • Picture of Daniel Lombardo
    Fri, Apr 26, 2013, 3:46 PM
    Ok great, how can we move this forward and get it ready for 2.4 and 2.5. We need to check students work to stop them from copying off each other for written assignments. Let me know if there will be a solution soon.
  • Picture of Daniel Lombardo
    Fri, Apr 26, 2013, 4:09 PM
    I don't know if this is a fair thing to do, but another developer has offered to update the plugin, the price is kinda high and i can't get it through our budget at this time. If anyone else wants to pitch in, we can each pay him separately and then we can publish it here to the community for free. Please send me a message if you are interested.

    The developer is a reputable member of this community and maintains several other plagiarism plugins.
  • Picture of Daniel Lombardo
    Sun, Apr 28, 2013, 12:52 PM
    Alright, I made a crowd-sourcing pledge on the service Indiegogo.

    If you need this plugin please contribute and it will be released in the community.
  • Picture of Daniel Villareal
    Fri, Aug 30, 2013, 11:37 AM
    Hi Sergey and Daniel.
    Good day. I have successfully installed crot on moodle 2.5 I also use it for local plagiarism but the only bug is how crot enable/disable properly. I only force enable crot. thank you..
  • Picture of Sergey Butakov
    Fri, Aug 30, 2013, 1:47 PM
    Thank you Daniel. As far as i understand from your email you made it compatible with 2.2 only.
    We've completed the development of the update. It will be released to the community in a week or so. Its fully compatible with 2.5 including type in assignments. You are welcome to join the tests once it is released to the public!
  • Picture of Sergey Butakov
    Thu, Sep 12, 2013, 8:44 AM
    The updated code has been released to github
  • Picture of Daniel Villareal
    Fri, Sep 13, 2013, 9:15 AM
    ok sir i will test the plugin thanks ^^
  • Picture of Daniel Villareal
    Fri, Sep 13, 2013, 9:23 AM
    Hi sir sergey. I modify the table names to install it on moodle 2.5. I placed it on /moodle/plagiarism and once I installed it I go to settings. then the same problem occur I can't enable and disable it properly thanks.
  • Picture of Christos Savva
    Thu, Sep 19, 2013, 5:43 PM
    I get this error when I try to install

    Coding error detected, it must be fixed by a programmer: Invalid table name {plagiarism_crot_submission_pair}: name is too long. Limit is 28 chars.

    Anyone knows how to fix it?
  • Picture of Christos Savva
    Thu, Sep 19, 2013, 5:48 PM
    Nevermind, fixed it by changing the variable NAME_MAX_LENGTH

    in /whome/moodle/lib/xmldb/xmldb_table.php (line 47)
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