This is about the mobile version of the online notebook.
No mobile app is developed currently. For mobile devices (pads or phones), if you visit the site from these devices, you will have an adapted site for you. Your home page will be a very simple note input box where you can make notes very quickly. You can make notes quickly on the mobile device even without internet access. (The notes you made is stored locally on your phone first and will get synced to the server once there is an internet connection.) You can save this page as a shortcut on your desktop/main screen or you can set it as your home page to allow easy access.
