Mavinote app
Mavinote lets you create and edit notes. It also lets you structure your notes by placing them in folders.
You can create a Mavinote account to synchronize your notes across your devices. Even after adding Mavinote account, you can still create folders and notes that reside only in your device by creating them in Local account. Anything created in Local account will not be available outside the device. Local account will be automatically created when you launch the application for the first time.
For more information about Mavinote, you can look at the project's repository.