If you thought we’ve already got enough Markdown editors on Mac, just add another one to your list Multimarkdown Composer. This one comes directly from Fletcher Penney, the guy who extended Markdown into MultiMarkdown. At first glance the app looks like an extended version of TextEdit with support for syntax coloring and auto-generating syntax. And it integrates very well with Marked.
As a user of a custom Markdown/MultiMarkdown syntax, I’m missing the option to configure MultiMarkdown Composer processor. But I hope it will come with a later version.
Multimarkdown Composer is selling at a special release $7.99 price in the App Store.