WPReady

The plugin works similar as shortcodes with important differences:
<ul>
<li>It looks for any tag in the post with the following format: {cf your_custom_field_name=your_custom_field_value}</li>
<li>For any tag found, it create a custom field for that post.</li>
<li>The tag is erased from the post.</li>
</ul>
<h4>How to use</h4>
Type in anywhere in a post: 
{cf your_custom_field_name=your_custom_field_value}
Examples:
<ul>
<li>{cf thumbnail=http://wordpressready.com/wp-content/uploads/oneringtorulethemall.jpg}</li>
<li>{cf posticon=/wp-content/uploads/posticon.ico}</li>
<li>{cf my_custom_color=#22fb30}</li>
</ul>
This three examples written inside the post will create three custom fields with respectives values 
when you publish the post. 
After publishing, the tag inside the post are deleted. No other information is erased.
<h4>Notes</h4>
<ul>
<li>Because the way the plugin works, it will run fine with ANY desktop blogger(Windows Live Writer, Scribefire, Qumana, w.Bloggar, Zoundry 
, Thingamablog, Blod Desk, Flock, Post2Blog, Bleezer, you name it)</li>
<li>The plugin can be used even inside the wordpress editor (though what would it be the point?)</li>
<li>You can use any number of custom field for post. </li>
<li>Reserved characters: ‘{cf’ and ‘}’,because it conflicts with the delimiters.</li>
<li>After the post, the tags are automatically erased.</li>
<li>If the custom field is already present, its value will be replaced.</li>
</ul>

Text to Custom Field

Allows adding custom fields from ANY desktop blog editor even if the editor can't support custom fields!

Walter Ebert

This plugin does more than just using the <code>xmlrpc_enabled</code> hook, because that is only used “To disable XML-RPC methods that require authentication”.
Activating this plugin will also disable pingbacks, trackbacks, and Really Simple Discovery (RSD), because these rely on XML-RPC.
It works with any webserver, because it does not use the .htaccess file.
<h4>Testing the plugin</h4>
From the command line you can test if the plugin is working correctly using <a href="https://curl.haxx.se/" rel="nofollow ugc">cURL</a>. Replace the <code>example.com</code> link to match your website:
<pre><code>curl -d '<?xml version="1.0"?><methodCall><methodName>system.listMethods</methodName><params><param><value><string/></value></param></params></methodCall>' https://example.com/xmlrpc.php
</code></pre>
This should only return the following methods: 
– <code>system.multicall</code> 
– <code>system.listMethods</code> 
– <code>system.getCapabilities</code>

Remove XML-RPC Methods

Remove all WordPress methods from the XML-RPC API to increase security.

Text to Custom Field vs Remove XML-RPC Methods