crimson090

Adds buttons to the Text (HTML) edit which generate Markdown syntax. These buttons serve as a great introduction to 
users who are new to Markdown, as well as shortcuts for more experienced users. The buttons include:
<ul>
<li>Bold</li>
<li>Italic</li>
<li>Blockquote</li>
<li>Link</li>
<li>Code</li>
<li>Table</li>
<li>Headers</li>
<li>Help (links to external Github Markdown guide)</li>
</ul>
This plugin does not modify the Visual editor, as that editor is not ideal for writing Markdown in. It’s recommended you disable 
the Visual editor entirely to enforce using Markdown.
Note that this plugin does not render Markdown. You should use a plugin (such as Jetpack Markdown) to render markdown in your theme.

MarkdownBar

Adds a toolbar of buttons to the Text (HTML) edit which generate Markdown syntax

mitchmac

The plugin creates zip files containing posts converted to Markdown. A WP-CLI command exists to handle exporting sites with a large amount of content.
<ul>
<li>Move WordPress content to Gatsby-friendly Markdown.</li>
<li>Customize the export! Remap and restructure exported fields.</li>
<li>CLI: Avoid PHP timeouts by using the command line with WP-CLI.</li>
<li>CLI: Export progress bar (great for large sites)!</li>
</ul>
<blockquote>
Reminder: always keep a backup of the WordPress database and files in case your export doesn’t work as expected!
</blockquote>
<h3>Working with Gatsby</h3>
If you’re just getting started with Gatsby, we recommend experimenting with a Markdown based Gatsby starter like <a href="https://github.com/tinacms/tina-starter-grande" rel="nofollow ugc">Tina Grande</a>. Installation is as easy as:
<pre><code>git clone https://github.com/tinacms/tina-starter-grande.git

cd tina-starter-grande

yarn install && gatsby develop
</code></pre>
Then copy your exported WordPress Markdown into the <code>content</code> directory or point the wp gatsby-markdown-export command at the content directory.
Want to port your WordPress or HTML theme to Gatsby? Checkout <a href="https://www.gatsbyjs.org/docs/porting-an-html-site-to-gatsby/" rel="nofollow ugc">Porting an HTML Site to Gatsby</a> for tips.
<h3>Command Line Usage</h3>
The command line functionality uses WP-CLI to interact with WordPress. <a href="https://wp-cli.org/#installing" rel="nofollow ugc">WP-CLI is easy to install</a> if you haven’t already.
Once it’s installed, you can export content to a directory like this:
<pre><code>wp gatsby-markdown-export --directory=/example/gatsby-starter/src/content
</code></pre>
All CLI arguments are optional.
 Option 
 Description 
 Default value
 <code>--help</code> 
 get help
 <code>--directory=</code> 
 export output directory 
 random temp directory
 <code>--post_types=</code> 
 post types to export, see: https://developer.wordpress.org/reference/classes/wp_query/#post-type-parameters 
 page,post
 <code>--post_status=</code> 
 post status to export, see: https://developer.wordpress.org/reference/classes/wp_query/#status-parameters 
 any
 <code>--fields_to_markdown=</code> 
 fields to convert to Markdown 
 excerpt
 <code>--excluded_front_matter=</code> 
 fields to exclude from front matter
 <code>--post_date_format=</code> 
 format for post publish date, see: https://www.php.net/manual/en/function.date.php 
 c
 <code>--upload_dir=</code> 
 directory in the export to copy WordPress uploads 
 uploads
 <code>--remap_fields=</code> 
 remap front matter field names, example: find1,replace1;find2,replace2
 <code>--fields_to_array=</code> 
 convert single value front matter fields to arrays
 <code>--include_private_fields=</code> 
 private post meta fields to include (they start with _)
 <code>--skip_copy_uploads</code> 
 flag, skips copying WordPress uploads to the export
 <code>--skip_original_images</code> 
 flag, skips the use of original dimension images
 <code>--skip_enforce_charset</code> 
 flag, skips use of blog_charset for the XML charset
 <code>--create_type_directory</code> 
 flag, creates directories based on post type

WP Gatsby Markdown Exporter

Export WordPress content to Markdown for GatsbyJS.

MarkdownBar vs WP Gatsby Markdown Exporter