Best plagiarism checker?

Hello! I'm finishing up a draft of my personal statement right now. I did use several sources for inspiration, so I just wanted to see how the internet defines plagiarism to make sure nothing in my essay is deemed "plagiarized" . When I was a student, turnitin.com was not widely used yet, so I'm unfamiliar with this stuff. Can anyone recommend me a good plagiarism checker? I am willing to pay a small fee but free is definitely the best! Thank you!
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums