Boostnote - Boostnote is an open-source note-taking app.
Journaley - A simple and elegant open-source journal keeping software for Windows compatible with Day One
OpenNote - An open web-based alternative to Microsoft OneNote and Evernote.
Daybook - Daybook is an application that allows you to record activities, experiences, thoughts, and entire ideas throughout a day and protect all of your information with a strong password.
GloboNote - GloboNote is a free and easy to use desktop note taking application.
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.