The “Markdown Editor App” is a simple but powerful Google Chrome App for working with Markdown and other text based file formats. It is a basic Markdown editing tool, which works even offline. You can install it on Chrome on Windows, Linux, Mac and ChromeOS (Chromebooks).
It also supports few keyboard shortcuts like CTRL + P for showing HTML preview of the entered Markdown text. You can open Markdown and other text based files with it. On ChromeOS, it can be set as the default application for dealing with markdown files.

Update: We have discontinued this Chrome App, as Google is going to end support for Chrome Apps soon. Read more about it here:
https://blog.chromium.org/2020/08/changes-to-chrome-app-support-timeline.html
@ToddA: Yeah, unfortunately, we have removed this Chrome app from the Chrome Web Store, as Google is going to end support for all Chrome Apps soon. You can read more about it here: https://blog.chromium.org/2020/08/changes-to-chrome-app-support-timeline.html
Appears to have been removed from Chrome Web Store — install link above is broken.
brilliant app, works smoothly. great job!
Nice app.
Surprised to see the cool user interface in the latest update. Well done.