Although I have not had experience with a freelance editor but I have used online copy editing service. In my first semester, I was not confident about my document security. Still, I have to believe someone in order to get my work done on time. So I approached a service called papertrue Their online chat assured me about my document security. So I did some research and read their privacy policy. When it comes to a service like this be sure to see their confidentiality condition as mentioned. If not I would suggest to look for some other service.