Oak Outliner seems to be pretty much the same as Little Outliner. This is what the Website tells you: "You didn't need a password because this outline is stored in your web browser's local storage. It can only be seen from your computer."
It cannot do much either! I have no real use for it. In some ways I prefer Fargo which can save to DropBox, but I do not see any advantages in writing my essentially private outlines in a Web Browser.
It does folding, however!