Patrick Sletvold

Content Security Policy Manager is a WordPress plugin that allows you to easily configure <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP" rel="nofollow ugc">Content Security Policy headers</a> for your site. You can have different CSP headers for the admin interface, the frontend for logged in users, and the frontend for regular visitors. The CSP directives can be individually enabled, and each policy can be set to enforce, report or be disabled.
Please note that this plugin offers limited help in figuring out what the contents of the policy should be. It only lets you configure the CSP in a easy to use interface.

Content Security Policy Manager

Plugin for configuring Content Security Policy headers for your site. Allows different CSP headers for admin, logged inn frontend and regular visitors

Jose Mortellaro

It helps in preventing Cross Site Scripting (XSS) with just a few lines of code.
Just activate it, no settings, no bloat.
It will not stop all the Cross Site Scripting injections, but with a very few lines of code you will drastically increase the security of your website without worsening the performance.
You can read more about what it does at <a href="https://josemortellaro.com/how-to-prevent-cross-site-scripting-xss/" rel="noopener nofollow ugc">https://josemortellaro.com/how-to-prevent-cross-site-scripting-xss/.</a>.
<h3>Help</h3>
If you need help open a thread on the support forum of this plugin. 
Please, before posting enable the debugging in wp-config.php. Need a step-by-step guide? Read <a href="https://freesoul-deactivate-plugins.com/how-to-enable-debugging-in-wordpress-a-step-by-step-guide/" rel="nofollow ugc">this detailed tutorial</a> on <a href="https://freesoul-deactivate-plugins.com/how-to-enable-debugging-in-wordpress-a-step-by-step-guide/" rel="nofollow ugc">how to enable debugging in WordPress</a> to learn more.

Basic Security: Prevent Cross Site Scripting

It helps in preventing Cross Site Scripting (XSS) with just a few lines of code.

Content Security Policy Manager vs Basic Security: Prevent Cross Site Scripting