Vladimir Kolesnikov

Adds the referrering link from which a commenting user came from to comment notifications and Comments screen in the Admin panel of your site.
This is an extended version of Donncha’s <a href="https://wordpress.org/extend/plugins/comment-referrers/" rel="ugc">Comment Referrers</a> plugin
ICS Comment Referrer:
<ul>
<li>uses both server (HTTP Referer header) and client (works if JavaScript enabled) referrer identification;</li>
<li>cryptographically protects the server-generated referrer field;</li>
<li>adds referring links to comment notifications;</li>
<li>shows referring links in Admin Panel » Comments.</li>
</ul>
<h3>Contributors</h3>
<ul>
<li><a href="http://blog.sjinks.pro/" rel="nofollow ugc">Vladimir Kolesnikov</a></li>
<li><a href="https://launchpad.net/~rahermosillac" rel="nofollow ugc">Ricardo A. Hermosilla Carrillo</a></li>
<li><a href="https://launchpad.net/~pierre-slamich" rel="nofollow ugc">Pierre Slamich</a></li>
<li><a href="https://launchpad.net/~sunder67" rel="nofollow ugc">zeugma</a></li>
<li><a href="https://launchpad.net/~elkan76" rel="nofollow ugc">Mauricio Peñaloza S.</a></li>
</ul>
<h3>Bug Reports</h3>
Please use <a href="https://bugs.launchpad.net/wp-plugin-comment-referrer/+filebug" rel="nofollow ugc">Launchpad</a> to report any bugs.

ICS Comment Referrer

Adds the referrering link from which a commenting user came from to comment notifications and Comments screen in the Admin panel of your site.

Medium Interactive

MDI HTTP Referer Block enables WordPress site owners to detect and control user experience based on the origin of traffic. By analyzing the HTTP referrer (both server-side via PHP and client-side via JavaScript when headers are missing), this plugin makes it easy to apply different behavior for visitors arriving from ads, social platforms, or syndicated search networks.
You can define specific referrer domains or patterns, and when a visitor matches those conditions, the plugin can:
<ul>
<li>Display a small notification (server-side) showing the detected referrer host or path.</li>
<li>Hide or reveal specific elements on your site using CSS selectors.</li>
<li>Redirect visitors from certain sources to a different URL.</li>
</ul>
This gives marketers, advertisers, and site owners fine control over how different audiences see the site.
Example use cases:
<ul>
<li>Hide contact forms when users arrive through syndicated search traffic to prevent spam or low-quality leads.</li>
<li>Hide pricing details when a user comes from social media to encourage engagement before pricing exposure.</li>
<li>Redirect visitors from affiliate networks to a dedicated landing page.</li>
<li>Show a simple banner confirming that the user arrived via a partner campaign.</li>
</ul>
The plugin sets a tracking cookie (<code>mdi_syndicated_ref</code>) to remember the detected source for the configured number of days, ensuring consistent visibility rules on repeat visits.
MDI HTTP Referer Block helps you tailor on-site experiences dynamically based on real visitor origin — simple, server-side controlled, and privacy-respecting.
For a full guide on blocking syndicated search traffic (e.g., Google Ads Performance Max), see: 
https://mediuminteractive.com/how-to-block-syndicated-search-traffic-from-performance-max-campaigns-in-google-ads/

MDI HTTP Referer Block

Hide elements or redirect users based on referrer domains. Useful for blocking partners, scrapers, or altering content per source.

ICS Comment Referrer vs MDI HTTP Referer Block