SourceTag

Form Setup

Set up SourceTag with Forminator

Forminator is a free form builder plugin by WPMU DEV for WordPress. This guide shows how to add SourceTag hidden fields to your Forminator forms so attribution data flows into your form submissions.

What you need

  • SourceTag installed on your site (script tag or WordPress plugin)
  • Forminator plugin installed and a form created

Step 1: Open your form in the Forminator editor

Go to Forminator > Forms in your WordPress dashboard. Click Edit on the form you want to add attribution fields to.

[IMAGE: Screenshot of the Forminator forms list in the WordPress dashboard]

Step 2: Add hidden fields

In the Forminator form editor:

  1. Click Insert Fields (the plus button)
  2. Scroll down to the Advanced section
  3. Click Hidden Field
  4. A new hidden field is added to the form

Repeat this for each SourceTag field you want to capture.

[IMAGE: Screenshot of the Forminator field types panel showing the Hidden Field option under Advanced]

Step 3: Set the field name

For each hidden field:

  1. Click on the hidden field in the form editor to open its settings
  2. In the Label field, enter the SourceTag field name (e.g. st_fc_channel)
  3. Under Advanced, check the field name/ID. Forminator generates a field name based on the label. Make sure the resulting field name matches the SourceTag field name exactly.
  4. Leave the Default Value empty

If Forminator modifies the field name (e.g. adding a prefix or changing the format), you can manually set the field name in the field’s advanced settings to match exactly.

[IMAGE: Screenshot of a Forminator hidden field settings panel with the label set to st_fc_channel]

Core fields (add these)

Add a hidden field for each of the following. These are the essential attribution fields:

  • st_fc_channel
  • st_fc_detail_1
  • st_fc_detail_2
  • st_fc_detail_3
  • st_fc_detail_4
  • st_lc_channel
  • st_lc_detail_1
  • st_lc_detail_2
  • st_lc_detail_3
  • st_lc_detail_4
  • st_fc_landing_page
  • st_lc_landing_page

Optional extended fields

If you’ve enabled extended field groups in your SourceTag dashboard, also add hidden fields for those. Common ones include:

  • st_fc_source and st_lc_source (raw UTM source)
  • st_fc_medium and st_lc_medium (raw UTM medium)
  • st_fc_campaign and st_lc_campaign (raw UTM campaign)
  • st_fc_click_id and st_lc_click_id (click IDs)
  • st_fc_click_id_type and st_lc_click_id_type (click ID types)
  • st_visits (visit count)
  • st_days_to_convert (days since first visit)
  • st_device (device type)
  • st_submit_page (page where the form was submitted)

See Captured Fields for the full list of available fields.

Step 4: Save and test

  1. Click Update to save your form
  2. Visit the page where the form is embedded, adding UTM parameters to the URL:
?utm_source=test&utm_medium=cpc&utm_campaign=forminator-test
  1. Open the browser developer tools (F12)
  2. In the Elements panel, find the Forminator form and look for the hidden input fields
  3. Verify the name attributes match the SourceTag field names and the value attributes are populated

Submit the form. Then check the submission:

  • Forminator entries: Go to Forminator > Forms > Submissions for your form. The hidden fields should appear in the entry.
  • Email notifications: If you have email notifications configured, the attribution data should be included.
  • CRM/integration: If you’re sending Forminator data to a CRM via a webhook or integration, make sure the hidden fields are included in the data mapping.

[IMAGE: Screenshot of a Forminator form submission entry showing populated SourceTag hidden fields]

Tips

  • Copy field names from the Fields page in your SourceTag dashboard. Each field name has a copy button to avoid typos.
  • Hidden fields are not visible to visitors when they fill in the form.
  • If you’re using Forminator’s quiz or poll modules (not the standard form module), hidden fields work the same way.
  • Forminator forms render as standard <form> HTML elements, so SourceTag’s auto-detection works reliably.
  • If you’re using Forminator’s AJAX submission (the default), the hidden fields are included in the submission data automatically.

Troubleshooting

Hidden fields not populated: Make sure the SourceTag script is loading correctly. Check the browser console for errors and verify the _sourcetag cookie exists in Application > Cookies.

Field names don’t match: Forminator may add a prefix or suffix to field names. Inspect the rendered form HTML in the browser developer tools to see the actual name attribute on the hidden input. The name must match what SourceTag expects.

Submissions not showing attribution data: If the hidden fields are in the form HTML with values but the submission doesn’t contain them, check Forminator’s submission settings. Some configurations may exclude empty or hidden fields from notifications.

Further reading