Several online plagiarism checkers offer free services for college papers, including Plagtracker and Brian Klug's plagiarism checker on Dustball.com. ScanMyEssay also offers a free download of Viper, a plagiarism checker application for Windows operating systems.
Plagtracker offers limited plagiarism checks on its website at no cost. It runs a brief scan of text that is typed or copied and pasted into a text box. The text is placed into a queue, and the user is prompted to enter an email address for the results to be sent to when the scan is complete. The site only allows one free check at a time for non-members. Plagtracker's website features numerous testimonials and reviews, and its premium service offer file uploads and supports multiple languages.
The Plagiarism Checker by Brian Klug featured on Dustball.com features a text box very similar to Plagtracker's. This free plagiarism checker is limited to 1,000 total free checks per day worldwide from all users, and once the website reaches its daily limit, it informs users that no more checks are available until the next day. The Plagiarism Checker does offer a subscription service, which bypasses the daily limit.
The Viper application is available for download from websites such as ScanMyEssay. Viper is completely free to download, and it claims access to over 10 billion scanned resources.