"Toast UI Editor", GFM Standard + Chart & UML Extensible.
"LaTeX editor for the GNOME desktop. ... The idea of LaTeXila is to always deal directly with the LaTeX code, while simplifying as most as possible the writing" (ib., 2017-03-07)
"an in-browser semantic rich text editor component" with
(ib., 2016-11-25) See also https://github.com/prosemirror/
"text editor for various markup languages"
"Online cloud based HTML5 filled Markdown Editor. Sync with Dropbox, Github and Google Drive. 100% Open Source!"
"Full-featured, open-source Markdown editor based on PageDown"
"text editor using the GTK2 toolkit with basic features of an IDE"
"a fast markdown processor for writing professional articles, books, manuals, webpages and presentations, with a focus on simplicity and plain text readability."
"An open source database-less blogging platform or flat-file blog [that] prioritizes simplicity and speed, written in PHP." (2016-12-03)
Forwared to http://ace.c9.io/
text editor/word processor for MS-DOS and Windows console mode
"integrated environment for writing LaTeX documents"