Set up SourceTag with Formstack

Formstack’s form builder includes a Hidden field type. You add one field per SourceTag data point and set the field label to match.

What you need

• SourceTag installed on your website
• A Formstack account
• The form embedded on your site using the JavaScript embed (not iframe)

Step 1: Open your form in the Formstack builder

Log in to Formstack and open the form you want to track.

Step 2: Add hidden fields

1. In the form builder, look at the Field Types panel on the left
2. Under Standard or Advanced fields, find Hidden
3. Drag or click to add a Hidden field to your form
4. Repeat for each SourceTag field

Core fields (add these)

Add a hidden field for each of the following:

• 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 have enabled extended field groups in your SourceTag dashboard, also add:

• st_fc_click_id and st_lc_click_id (click IDs)
• st_visits (visit count)
• st_days_to_convert (days since first visit)
• st_device (device type)

See Captured Fields for the full list of available fields.

Step 3: Set the field label and name

For each hidden field:

1. Click on the hidden field in the form builder
2. Set the Field Label to the SourceTag field name (e.g. st_fc_channel)
3. Check the Field Settings area. Formstack generates a field name from the label. Make sure the resulting name attribute matches the SourceTag field name exactly
4. Leave the default value empty

If Formstack modifies the name (for instance by adding a prefix or number), check the field settings for a way to set a custom name or use the label as-is.

Step 4: Embed using JavaScript

When embedding the form on your site, use the JavaScript embed method. This renders the form in your page’s DOM so SourceTag can reach the hidden fields.

1. In Formstack, go to Publish or Share
2. Choose the JavaScript embed option
3. Copy the code and paste it onto your page

Avoid the iframe embed, as cross-origin restrictions will prevent SourceTag from accessing the form.

Step 5: Test

Visit the page with UTM parameters:

?utm_source=test&utm_medium=cpc&utm_campaign=formstack-test

Submit the form. In Formstack, go to Submissions and check the test entry. The hidden fields should contain your attribution data.

Tips

• Copy field names from the Fields page in your SourceTag dashboard to avoid typos.
• Hidden fields do not appear to visitors when the form is rendered.
• If you are using Formstack integrations (Salesforce, HubSpot, etc.), map the hidden fields to the corresponding CRM properties.
• Formstack’s JS embed is the most reliable method. If you are embedding via WordPress, the Formstack WordPress plugin renders via JS by default and should work fine.