Typora - A minimal Markdown reading & writing app.
Xed - A text editor forked from Pluma and Gedit. Xed is the default text editor of Linux Mint.
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
Caret Editor - Caret Editor is an editing tool for Chrome OS that is used for editing texts or codes.
StackEdit - Full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.
Nova Code Editor - Nova Code Editor is software that is used for writing and editing codes.