Max Cutler

Uses PHP’s output buffering to buffer XML-RPC responses and strip superfluous whitespace.
Plugins, themes, and any other files executed during the WordPress load process can unintentionally emit whitespace, 
such as by including a newline character after an explicit closing “?>” PHP tag instead of letting PHP auto-close the 
file.

XML-RPC De-whitespacer

Removes leading and trailing whitespace from XML-RPC responses that can break some XML-RPC clients.

Pascal CESCATO

Stop XML-RPC Attacks protects your WordPress site from XML-RPC brute force attacks, DDoS attempts, and reconnaissance probes while maintaining compatibility with essential services like Jetpack and WooCommerce.
Features:
<ul>
<li>Three security modes: Full Disable, Guest Disable, or Selective Blocking</li>
<li>Blocks dangerous methods: system.multicall, pingback.ping, and more</li>
<li>Compatible with Jetpack and WooCommerce</li>
<li>Optional user enumeration blocking</li>
<li>Attack logging for monitoring</li>
<li>Zero configuration required – works out of the box</li>
<li>Clean, intuitive admin interface</li>
</ul>

Stop XML-RPC Attacks

Blocks dangerous XML-RPC methods while preserving Jetpack, WooCommerce, and mobile apps compatibility.

XML-RPC De-whitespacer vs Stop XML-RPC Attacks