turnitin dot com works for my dad, hes a teacher, it automatically searches the web to make sure the work isn't plagiarized. You may have to make an account though.
If you didn't copy your work from something then your not plagiarizing. If you do copy something site where you got it from and put it in quotations.
Teachers say they check people's papers by typing in a few sentences to see if they have copied & pasted or copied down on someone else's work
turnitin is awesome! but it's mostly used for academics
www yourownbrain .com
It always works for me.