Ghaas Technologies Pvt. Ltd

UTM Master helps you capture and preserve UTM parameters in cookies for attribution and tracking. Features include:
<ul>
<li>Auto-save UTM parameters (<code>utm_source</code>, <code>utm_medium</code>, etc.)</li>
<li>Support for custom UTM parameters</li>
<li>Append UTM to all site links and CTAs</li>
<li>GDPR-compliant consent banner</li>
<li>Shortcode to retrieve current and original UTM values</li>
</ul>

UTM Master

Store UTM parameters in cookies, append them to links automatically, and manage GDPR compliance easily.

shawfactor

This plugin does tracking/grabbing properly by tracking the data by localstorage only, rather than cookies or session variables. This is a superior way of tracking this data as it does not impact your server or break caching in any way.
It does so by including the Bill Franklins fantastic lightweight JavaScript library for this. I will be including thiis data automatically in my own plugins. But you can access intrsuctions and examples on how access this data in your own opt in forms here:
https://github.com/bilbof/purser

LH UTM Tracking

The proper way to capture UTMs on your (optin) forms.

UTM Master vs LH UTM Tracking