seothemes

Markdown Editor replaces the default WordPress editor with a Markdown editor for your posts and pages. This plugin uses the Jetpack Markdown module for converting Markdown into HTML and plays nicely with Jetpack if both plugins are installed.
There are 4 editor layouts to choose from when writing posts: default, preview, full-screen and split screen. Changes are updated automatically allowing you to preview your content as you write.
By default Markdown Editor is only enabled on Posts, but you can enable it on pages and custom post types by adding post type support. For example to add Markdown support to Pages, add the following line of code to your theme’s functions.php file:
<pre><code>add_post_type_support( 'page', 'wpcom-markdown' );
</code></pre>
To add Markdown support to a ‘Product’ custom post type, add this to your theme’s functions.php file:
<pre><code>add_post_type_support( 'product', 'wpcom-markdown' );
</code></pre>
<h3>Syntax Highlighting</h3>
By default, Markdown Editor enables syntax highlighting for code blocks. This can be removed by adding the following line of code to your theme’s functions.php file:
<pre><code>add_filter( 'markdown_editor_highlight', '__return_false' );
</code></pre>
The click to copy button can be removed with the following line:
<pre><code>add_filter( 'markdown_editor_clipboard', '__return_false' );
</code></pre>

Markdown Editor

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Kills WordPress

Replaces the default WordPress editor with a Markdown editor for your posts and pages.

kennydude

MarkItUp (beta) allows for you to use Markdown on your WordPress site.
It does this on a per-author basis and per-post. This means that you shouldn’t be accidently converting other people’s posts/pages into Markdown by accident!
Currently this wears the beta label because it could have little bumps which aren’t smoothed out just yet.

MarkItUp!

MarkitUp (beta) is a wordpress plugin which allows you to use Markdown on your site without breaking existing content

Markdown Editor vs MarkItUp!