Marked.js - A full-featured markdown parser and compiler, written in JavaScript. Built for speed.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Markdeep - Advanced Markdown renderer for the browser with full diagram support
Standard Notes - A safe place for your notes, thoughts, and life's work
Strapdown.js - Instant and elegant Markdown documents in the browser.
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.