Do you know any editor for Mac OSX that helps with editing Github flavored markdown?
I think Mou ( http://mouapp.com/ ) is fine, only that its just plain markdown and not Github markdown.
Please, this is a question about Github flavored Markdown, and not about plain Markdown!! for example I think javascript syntax highlighting is really nice. not only does Mou not support it, it also destroys the layout of the code.
GitHub created a new open-sourced editor called Atom that provides a built-in real-time Markdown Preview.
Fire it up with Control+Shift+m and you'll get a great experience that looks similar to this (except with your own Atom theme applied):
Atom uses packages to provide plugin functionality. Read more about the Markdown Package on Github.
If you use Emacs, markdown-mode.el offers a mode for Github-flavored Markdown.
(If you don't use Emacs, you're probably not well advised to pick it up just for this sole purpose. It isn't so much a text editor, as a virtual Lisp machine in which has been implemented a text editor whose conventions are quite unlike those of any other such tool; Emacs in fact has its own standard library, which in the current release (version 24.3, March 2013), weighs in at 172M of source. There is nothing you can do in any other text editor which you can't do in Emacs, often more quickly and efficiently; the trade-off is that, depending on your purpose, you will first need to spend anywhere from several days to several years first acquiring expertise in the use of Emacs.)
I had hoped the Mou developer would show the good sense of implementing a reasonably general parser which could accept a language specification, in order that his code could eventually support more dialects of Markdown than just the canonical one. Were that true, it would be trivial to modify Mou for Github-flavored Markdown -- but, regrettably, on examining the app bundle's contents, I find this appears not to be the case.
Covering what I understand to be the popular OS X editors, TextMate can apparently be made to support Github-flavored Markdown. I gather there is also a Github-flavored Markdown plugin for Sublime Text's newer versions, although why anyone would want to pay $70 for such a fundamental capability as text editing is beyond me. BBEdit doesn't seem to have a module, or at least I can't find one via Google, but does anyone use BBEdit any more anyway? And, finally, you'd really expect there would be a plugin for Xcode, but I haven't been able to find one for that, either.
And, finally, examining a slightly different approach, Marked is an OS X-native Markdown previewer which has Github-flavored Markdown parsing built in; the way this works is, you edit the Markdown source in the editor of your choice, and Marked updates its rendering of the file to show you what the result will look like. I haven't used it myself, but it looks like it might be of use. (Sure, it costs money, but $4 won't even buy you a deck of smokes or a gallon of gas these days, so it's not like it costs enough to care about.)
You should definitely try StackEdit. I personally love it and stay with it after having tried Mou, Atom, all kind of editor/ide plugins etc.
StackEdit is a free, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.
Read the complete feature list here.
There are stylings for vim that support github markdown. I'm taking vim as an example here because I'm a vim user, but I suspect there are comparable plugins / styles for other text editors.
If you don't mind running the markdown editor as a local HTML file inside your browser, consider downloading jbt/markdown editor. There a preview of how it works here. I downloaded the source, and now just double click the HTML file every time I want to edit markdown files. It supports some interesting features like pressing ctrl+s to save as a .md file, supports dragging / dropping files into the browser to edit them, etc.
Should you ever want to get the HTML generated by the editor, (using Firefox) I select the all generated HTML on the right of the editor -> right click -> view selection source.
