Joseph Scott

Work around for some versions of libxml2 2.7.x that strip out brackets when parsing XML. This plugin fixes XML-RPC requests that are mangled because of this problem. The real fix for this (making the use of this plugin unnecessary) is to use PHP 5.2.9+ with libxml2 2.7.3+.
For more information about this problem see <a href="https://core.trac.wordpress.org/ticket/7771" rel="nofollow ugc">https://core.trac.wordpress.org/ticket/7771</a>.

LibXML2 Fix

Work around for some versions of libxml2 2.7.x that strip out brackets when parsing XML.  This plugin fixes XML-RPC requests that are mangled because  …

DeveloperWil

Completely disables the XML-RPC API which was introduced in WordPress 3.5 and above which lets remote clients post, upload and edit content.
Notes: 
If you are using the WordPress smart phone app or the Jetpack plugin, please note that they need this service enabled.
If you activate this plugin your WordPress phone app will not be able to connect to your site and Jetpack will not be able to connect to wordpress.com where site visitor data (and other stuff) is stored.
Other plugins and services that use the XML-RPC API will also not function properly.
<h4>Plugin Page</h4>
<a href="https://zeropointdevelopment.com/wordpress-plugins/deactivate-xml-rpc-service-wordpress-plugin/" title="Deactivate XML-RPC Service WordPress Plugin" rel="nofollow ugc">Deactivate XML-RPC</a>

Deactivate XML-RPC Service

Disables the XMP-RPC API service introduced in WordPress 3.5 and above.

LibXML2 Fix vs Deactivate XML-RPC Service