MOSS is a free service hosted by Stanford University. Faculty submit a set of software source code files turned in by students for a particular programming assignment and the MOSS server produces web pages listing pairs of programs with similar code.  MOSS also highlights individual passages in programs that appear the same, making it easy to quickly compare the files.  Finally, MOSS can automatically ignore matches on the parts of the assignments that one expects to be shared (e.g., software libraries or instructor-supplied code), thereby eliminating false positives that arise from legitimate sharing.

To obtain a Moss account, send a mail message to The body of the message should appear exactly as follows:

    mail username@domain (your email address)
If you already have an account, the latest submission script can be downloaded here and additional information is available here: MOSS.