Lister
This app runs in the browser and saves your lists in the browser's local storage. It means that no data is sent to the server.
The app has a reorderable list and a plain text editor aside to sync each other. Items in the list are separated by newlines in the text editor. It is designed to help you reorder list items easily by dragging and dropping. If the items have the numbered prefix like "1. ", "2. ", ..., the prefix will be automatically updated when you reorder them.