Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Encrypted Notepad - Encrypted Notepad is a very simple to use application providing state of the art...
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
Notebook PEA - Protects your private notes with a password.
Standard Notes - A safe place for your notes, thoughts, and life's work
Paranoia Text Encryption - Paranoia Text Encryption encrypts text according to a choice of strong algorithms.