Nano Editor
GNU nano is a small editor for on the terminal. It supports syntax highlighting, spell checking, justifying, completion, undo/redo...
CLI text editor
ProseMirror
In-browser structured text editing component
Org mode
Org: an Emacs Mode for Notes, Planning, Authoring and more!
GNU Emacs
jEdit
Vim
Neovim.io
vim out of the box
BlueGriffon
BlueGriffon, the next-gen Wysiwyg Web Editor