Beaver Notes - Your personal note-taking haven for privacy and efficiency.
Typora - A minimal Markdown reading & writing app.
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.
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Minimalist Markdown Editor - This is the simplest and slickest Markdown editor.