PDFProtectFree is a quite useful and safe utility that protect your PDF files. You can add user password to prevent anyone except you from opening and looking over your document. So, your privacy will be protected. Meantime, you can also add owner password to restrict the permissions of your PDF files. There are eight options you can choose to restrict the permissions, such as extraction printing, HD printing, modification, copying, comments, screen reader, form filling. After you have set owner password on a protected PDF file, the users are unable to use these restricted permissions.