Plag Tracker is a nice site that I just found out about for checking for plagiarism. All a user has to is upload a document and then PT scans it for plagiarism. A detailed report is then given for results.
I recommend checking out Plag Tracker by clicking here!!
Thanks to Education Technology Guy for the tip.
Also, try Eduify , Plagiarisma, and Paper Rater for plagiarism checkers.