What is JPlag

JPlag is a system that finds similarities among multiple sets of source code files. This way it can detect software plagiarism. JPlag does not merely compare bytes of text, but is aware of programming language syntax and program structure and hence is robust against many kinds of attempts to disguise similarities between plagiarized files. JPlag currently supports Java, C#, C, C++, Scheme and natural language text. Its capabilities can be extended via front ends.

JPlag is typically used to detect and thus discourage the unallowed copying of student exercise programs in programming education. But in principle it can also be used to detect stolen software parts among large amounts of source text or modules that have been duplicated (and only slightly modified). JPlag has already played a part in several intellectual property cases where it has been successfully used by expert witnesses.

JPlag has a powerful graphical interface for presenting its results. See our example.

Just to make it clear: JPlag does not compare to the internet! It is designed to find similarities among the student solutions, which is usually sufficient for computer programs.

Use JPlag

Please download JPlag frm Github (

Official Website

Visit the official website: for more information!

Papers about JPlag

There are some papers about the technology of JPlag as well as comparisons to other plagiarism detection tools. View the list of publications.

Development Documentation

READ FIRST: DevelopmentGuidlines

Last modified 6 months ago Last modified on Apr 7, 2015 9:08:42 AM