This is something I need to do more of. I've used Amazon and a couple of others. I currently have one for ProWriting Aid that I really like. It's a program I use, so I don't mind sharing it, and their affiliate program is easy. It's a program that lets you paste in your chapter, and then it gives you feedback like a first level editor. I also like SmartEdit Lite for that, but I'm not an affiliate. Yet.