Max Cutler

This plugin brings XML-RPC API enhancements from the WordPress 3.4 release to previous versions 
of WordPress (3.3 and earlier). It also adds new user management methods.
It is derived from Prasath Nadarajah’s GSoC ’11 project to expand WordPress’ web services, 
although the exposed API methods are not compatible (different parameter names/types/orders).
<h4>Methods</h4>
New Methods:
<ul>
<li>wp.newUser – create a new user</li>
<li>wp.editUser – edit user information</li>
<li>wp.deleteUser – delete a specfic user</li>
</ul>
3.5 Methods for pre-3.5 sites:
<ul>
<li>wp.getUser – get information about a specific user</li>
<li>wp.getUsers – retrieve a list of users</li>
<li>wp.getProfile – retrieve information about the requesting user</li>
<li>wp.editProfile – edit the profile of the requesting user</li>
<li>wp.getRevisions – retrieve revisions for a specific post</li>
<li>wp.restoreRevision – restore a post revision</li>
</ul>
3.4 Methods for pre-3.4 sites:
<ul>
<li>wp.newPost – create a new post (of any post type)</li>
<li>wp.editPost – edit a post (of any post type)</li>
<li>wp.deletePost – delete a post (of any post type)</li>
<li>wp.getPost – get a specific post (of any post type)</li>
<li>wp.getPosts – get a list of posts</li>
<li>wp.getPostType – get information about a specific post type</li>
<li>wp.getPostTypes – get a list of registered post types</li>
<li>wp.getTaxonomy – get information about a specific taxonomy</li>
<li>wp.getTaxonomies – get a list of registered taxonomies</li>
<li>wp.newTerm – create a new term in a taxonomy</li>
<li>wp.editTerm – edit a term in a taxonomy</li>
<li>wp.deleteTerm – delete a term in a taxonomy</li>
<li>wp.getTerm – get information about a specific term in a taxonomy</li>
<li>wp.getTerms – get a list of term associated with a taxonomy</li>
</ul>

XML-RPC Modernization

excelent

This plugin updates the WordPress XML-RPC API to leverage the latest features of WordPress and move beyond the historical Blogger/metaWeblog/MT APIs.

Amin Nazemi

Neatma

Protect your website from xmlrpc brute-force attacks,DOS and DDOS attacks, this plugin disables the XML-RPC and trackbacks-pingbacks on your WordPress website.
PLUGIN FEATURES 
(These are options you can enable or disable each one)
<ul>
<li>Disable access to xmlrpc.php file using .httacess file </li>
<li>Automatically change htaccess file permission to read-only (0444)</li>
<li>Disable X-pingback to minimize CPU usage </li>
<li>Disable selected methods from XML-RPC</li>
<li>Remove pingback-ping link from header</li>
<li>Disable trackbacks and pingbacks to avoid spammers and hackers</li>
<li>Rename XML-RPC slug to whatever you want</li>
<li>Black list IPs for XML-RPC</li>
<li>White list IPs for XML-RPC</li>
<li>Some options to speed-up your wordpress website</li>
<li>Disable JSON REST API</li>
<li>Hide WordPress Version</li>
<li>Disable built-in WordPress file editor</li>
<li>Disable wlw manifest</li>
<li>And some other options</li>
</ul>
What is XMLRPC
XML-RPC, or XML Remote Procedure Call is a protocol which uses XML to encode its calls and HTTP as a transport mechanism. 
Beginning in WordPress 3.5, XML-RPC is enabled by default. Additionally, the option to disable/enable XML-RPC was removed. For various reasons, site owners may wish to disable this functionality. This plugin provides an easy way to do so.
Why you should disable XML-RPC 
Xmlrpc has two main weaknesses
<ul>
<li>Brute force attacks: 
Attackers try to login to WordPress using xmlrpc.php with as many username/password combinations as they can enter. A method within xmlrpc.php allows the attacker to use a single command (system.multicall) to guess hundreds of passwords. Daniel Cid at Sucuri described it well in October 2015: “With only 3 or 4 HTTP requests, the attackers could try thousands of passwords, bypassing security tools that are designed to look and block brute force attempts.”</li>
<li>Denial of Service Attacks via Pingback: 
Back in 2013, attackers sent Pingback requests through xmlrpc.php of approximately 2500 WordPress sites to “herd (these sites) into a voluntary botnet,” according to Gur Schatz at Incapsula. “This gives any attacker a virtually limitless set of IP addresses to Distribute a Denial of Service attack across a network of over 100 million WordPress sites, without having to compromise them.”</li>
</ul>

Disable XML-RPC-API

The upgrade notice keeps coming back on every screen even after being dismissed. It looks very unprofessional to my clients and is embarrassing for me as a web developer, i would rather disable the plugin and use the code in a function. 

It should be permanently dismissible via a cookie, like for other plugins. It might be ok once, when the plugin is first installed or updated, but after that, it should never appear again. 

Good plugin, but upgrade nag is too annoying

A simple and lightweight plugin to disable XML-RPC API, X-Pingback and pingback-ping in WordPress 3.5+ for a faster and more secure website

XML-RPC Modernization vs Disable XML-RPC-API