CotEditor - Open Source Plain-Text Editor for OS X
Trix - A rich text editor for everyday writing.
Sublime Text - Sublime Text is a sophisticated text editor for code, html and prose - any kind of text file. You'll love the slick user interface and extraordinary features. Fully customizable with macros, and syntax highlighting for most major languages.
BBEdit - BBEdit is a professional HTML and text editor for Macintosh that provides features for editing, searching, and minipulation of text for web authors and software developers.
Notepad++ - A free source code editor which supports several programming languages running under the MS Windows environment.
Draft.js - Rich Text Editor Framework for React