averageradical

Non-technical summary: Track incoming referrer and write it to any hidden form field with the identifier “referrer” (this can be created in Contact Form 7, for example; see below). Also if the WordPress site redirects from HTTP to HTTPS, this plugin also overrides the redirect to add the referrer to the https URL.
Technical details: This plugin runs client-side JavaScript in every page in HEAD and if there isn’t a session cookie with the name “referrer”, then it writes a session cookie with the name “referrer” and the value of either document.referrer, or if that’s empty, the URL-encoded value of window.location.href. There is another client-side JavaScript in every page before which writes the value of the “referrer” cookie to any INPUT with the ID “referrer”, if it exists.
When integrating with Contact Form 7, add a hidden input field such as the following:
<pre><code>[hidden referrer id:referrer]
</code></pre>
And then add to the Mail’s Message Body:
<pre><code>Referrer: [referrer]
</code></pre>
If you’re just integrating this with HTML, just add this to any form:
<pre><code><input type="hidden" id="referrer" name="referrer" />
</code></pre>

track-incoming-referrer

Track incoming referrer and write it to any hidden form field with the identifier "referrer".

codepeople

CP Referrer and Conversion Tracking is a useful tool for evaluating the result of marketing campaigns. It records the referral website of each visitor and it can also be used to identify the referral of the conversions (purchases, contact form submissions, appointments, bookings).
The main features are:
<ul>
<li>
Records the referrer (HTTP referer) of each website visitor (tracking logs)
</li>
<li>
Provides graphics / stats of referral websites and visitors (tracking stats)
</li>
<li>
Allow to create different referral links for different marketing campaigns (referral sources)
</li>
<li>
Records the original referrer and the latest referrer of the conversions
</li>
<li>
Includes integration with multiple plugins for tracking its conversions
</li>
</ul>
<h4>Recording the referrer</h4>
The CP Referrer and Conversion Tracking plugin implements an efficient way to detect and store the referral website when the HTTP referer header is present(when the user clicks on a link pointing to a webpage). This automatically identify for example when the user comes from Google, Facebook or from other external website.
The visitors with identified referrers are listed under the “Tracking Logs” menu. The referrer, IP address and time of the first visit is recorded as part of the logs.
To avoid storing a large number of referrer logs, the old logs are deleted as default every 90 days. This number of days to delete old logs can be edited from the plugin settings.
<h4>Graphics / stats of referral websites</h4>
The recorded logs are used to render graphics indicating the evolution of logs received per day, the logs received per hour and the referral websites identified.
Stats are provided also for logs received per year, during the latest 12 months, during the latest 12 weeks and during the latest 30 days. This helps to evaluate evolution of referrers and visitors during different periods of time. Note: These stats may be impacted by the automatic deletion of old logs.
This section is located under the plugin menu “Tracking Stats”.
<h4>Creating different referral links for different marketing campaigns</h4>
The purpose of this section is to create links for different marketing platforms, making easier to identify the referral.
For example you can setup a different entry point for a Google Adwords campaign and for a Facebook Ads, this way the exact referrer source will be reported even if the automatic HTTP referer info is not sent.
This section is located under the plugin menu “Referral Sources”.
<h4>Tracking Conversions</h4>
The CP Referrer and Conversion Tracking plugin can identify the referral of conversions, for example contact form submissions, purchases, bookings, appointment requests, etc…
The conversions are listed with the referrer of the initial visit and also with the referrer of the latest user session in the case the visitor used a different referrer for the latest sessions when the conversion happened.
To register the conversions the related add-on must be activated (add-ons are included in the plugin). Currently the plugin support several conversion add-ons for different plugins (contact forms, appointment requests, bookings, paypal payments) and we will be continuously working adding new integrations to identify conversions of third party plugins.
This section is located under the menu “Tracking Conversions”.
<h4>Tracking conversions originated in other plugins</h4>
The “Add Ons” menu already includes several conversion add-ons for different plugins, for example to track conversions like the following:
<ul>
<li>Contact forms</li>
<li>Quote request forms</li>
<li>Appointment bookings</li>
<li>General bookings</li>
<li>Polls</li>
<li>Payment forms </li>
</ul>
Includes conversion tracking for the following plugins:
<ul>
<li><a href="https://wordpress.org/plugins/woocommerce/" rel="ugc">WooCommerce</a></li>
<li><a href="https://wordpress.org/plugins/contact-form-7/" rel="ugc">Contact Form 7</a></li>
<li><a href="https://wordpress.org/plugins/contact-form-to-email/" rel="ugc">Contact Form to Email</a></li>
<li><a href="https://wordpress.org/plugins/appointment-hour-booking/" rel="ugc">Appointment Hour Booking</a></li>
<li><a href="https://wordpress.org/plugins/appointment-booking-calendar/" rel="ugc">Appointment Booking Calendar</a></li>
<li><a href="https://wordpress.org/plugins/booking-calendar-contact-form/" rel="ugc">Booking Calendar Contact Form</a></li>
<li><a href="https://wordpress.org/plugins/calculated-fields-form/" rel="ugc">Calculated Fields Form</a></li>
<li><a href="https://wordpress.org/plugins/cp-contact-form-with-paypal/" rel="ugc">Contact Form with PayPal</a></li>
<li><a href="https://wordpress.org/plugins/cp-polls/" rel="ugc">CP Polls</a></li>
<li><a href="https://wordpress.org/plugins/wp-time-slots-booking-form/" rel="ugc">WP Time Slots Booking Form</a></li>
</ul>
New add-ons will be added soon.
For developers: If you need to track a custom conversion writing the please see in the FAQ the supported hooks.

CP Referrer and Conversion Tracking

CP Referrer and Conversion Tracking registers how the website visitors reached the website, identifying the referral website. Also track conversions.

track-incoming-referrer vs CP Referrer and Conversion Tracking