typora

Typora is a minimal markdown editor, providing new ways for reading and
writing markdown. It is currently in beta.

Typora is commercial software (not open source), but is free during beta.
Typora on GitHub supports collaboration between its developer, Abner Lee,
and its user community, providing a place to transparently report issues,
collect feedback and discuss future direction. It also provides open
source resources for user customization of themes.