QLCommonMark is a QuickLook generator for CommonMark and Markdown files. It uses cmark to render the text, and Bootstrap to style it.

Download QLCommonMark.qlgenerator and copy it to your ~/Library/QuickLook or /Library/QuickLook folder. If the plugin is not picked up immediately, you may need to run qlmanage -r from the Terminal.

If you have Homebrew-Cask installed, you can install QLCommonMark with the following

$ brew update

$ brew cask install qlcommonmark

and uninstall using

$ brew cask uninstall qlcommonmark

This project was inspired by:

• ttscoff/MMD-QuickLook: Improved QuickLook generator for MultiMarkdown files
• toland/qlmarkdown: QuickLook generator for Markdown files.

Versatil Markdown is a CommonMark compliant Markdown editor for macOS, and incorporates QLCommonMark. You can check out a free trial on the Versatil Markdown website.