Turnitin is an Internet-based plagiarism-prevention service created by iParadigms, LLC, first launched in 1997.Typically, universities and high schools buy licenses to submit essays to the Turnitin website, which checks the documents for unoriginal content.Paradigms, the company behind Turnitin, runs another website called WriteCheck where students can submit their papers to be tested against the same database used by Turnitin, and determine whether or not their paper will be detected as plagiarism.