Tomboy - Apps/Tomboy - GNOME Wiki!
Writebox - Writebox is a simple and distraction-free text editor for Chrome and iPhone/iPad.
Turtl - The secure, collaborative notebook
Calmly Writer - Distraction-free text editor for Mac, Windows, Linux and ChromeOS.
Omni Notes - Note taking open-source application aimed to have both a simple interface but keeping smart behavior
Stashany - Online notepad for developers