When do you want it to save the file? After you hit a certain command? Microsoft word already has that. Just hit Ctrl+S. There's this one program that saves whatever you type in it automatically. Download Notepad++. When you close it, whatever you have written on it gets saved. Next time you open it, whatever was typed is still there. However it only does automatically for one instance. For example, you can't open it, type "Hi", close it, open it again, type "Hey", and open two instances of the program to find "Hi" and "Hey". Whatever was last one it, is what you will find next time you open it. It also features the Ctrl+S save shortcut.