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Free anti-plagiarism software for teachers and other professionals to review texts and check for plagiarism

Free anti-plagiarism software for teachers and other professionals to review texts and check for plagiarism

Vote: (107 votes)

Program license: Free

Program by: Kerigwa

Version: 1.5.00

Works under: Windows


Program license

(107 votes)


Program by




Works under:


Viper is a plagiarism-checking utility for Windows. One of the striking things about the Internet is the incredible access to information that it provides. Unfortunately, some students see this bounty as a temptation to cheat. Instead of submitting entirely original work, they turn in papers that attempt to pass off outside sources as their own writing. Viper is one of many tools of varying effectiveness that aim to help educators and other professionals recognize and put a stop to such cheating.

One of the simplest, crudest ways of checking for plagiarism is to submit selected portions of papers to major search engines like Google. While this method can help people identify the clumsiest attempts at plagiarism, it falls short against more sophisticated efforts. One problem is that search engines typically limit the length of the queries that can be submitted to them. In one respect, Viper serves as a special-purpose search engine. It indexes billions of online and offline documents in the same way as Google but with the specific aim of making this database available for plagiarism prevention.

Toward this end, Viper allows for searches of unlimited length. This means that entire academic papers, theses and dissertations can be checked in a single go. Furthermore, the tool permits users to resubmit those searches over and over again as needed; the types of minor changes typically inserted by sophisticated cheaters will not skew the results that Viper returns. Finally, when evidence of plagiarism is found, the program gives a straightforward side-by-side view of the suspicious text and potential copies. This allows educators to use their own judgment and decide if further action might be merited.

Overall, Viper compares very well to competing solutions like TurnItIn. Given the fact that all competitors seem to charge for access beyond brief trial periods, one surprising thing about Viper is that the software and service are offered entirely free of charge. A section of the Viper End User License Agreement does note that copies of essays and papers that users submit through the tool are stored on servers indefinitely, becoming part of the index that the software uses to detect plagiarism. This stipulation seems somewhat unusual and problematic, especially when you consider that teachers may not even have the legal right to let Viper retain students' papers in this manner.


  • Seems to be just as effective as other better-known tools for checking plagiarism.
  • Software is offered entirely free of charge.


  • Unusual legal claims may raise eyebrows and questions.