How to Use Advanced Landing Page Features

Why This Matters

Advanced landing page techniques let you create sophisticated lead capture systems that go beyond basic forms. URL prefilling eliminates friction by pre-populating contact information for known visitors. Hidden fields enable invisible tracking of campaign sources, ad IDs, or other metadata without cluttering your form with extra visible fields.

These techniques serve specific use cases: prefilling speeds up form completion for personalized email campaigns, while hidden fields track detailed attribution data for marketing analytics. Both require technical implementation but deliver powerful results when used appropriately.

This guide walks you through implementing URL prefilling and hidden fields on your landing pages.

Before You Begin

Understand that these are advanced techniques requiring technical knowledge—you'll be working with URLs, query parameters, and form field configurations that aren't visible in the standard interface.

These features only work with landing pages built using the Content Designer (the visual page builder). They don't work with older legacy landing page templates.

Know that URL prefilling should be used for convenience, not security. Visitors can view and modify URL parameters, so never prefill sensitive information or rely on locked fields for data integrity.

Have a landing page already created and configured, as you'll be modifying existing pages rather than building from scratch.

Step-by-Step Instructions

1. Understand URL Prefilling

URL prefilling lets you pass contact information through the URL to automatically populate form fields when visitors land on your page.

How it works: You add parameters to your landing page URL that tell the system which fields to fill with which values.

Use cases:

  • Personalized email campaigns where you know the recipient's information
  • Follow-up links sent to existing contacts
  • Event registration links with attendee names pre-filled
  • Reducing form friction for known contacts

Important limitations:

  • Prefilled data can be changed by modifying the URL (not secure)
  • Only works with Content Designer landing pages
  • Doesn't work with checkbox fields
  • Relies on exact field name matching (case-sensitive)

Time: 2 minutes to understand


2. Choose Your Prefill Type

URL prefilling offers two behaviors:

Prefill Type 1 (Editable Fields):

  • Add &prefill=1 to your URL
  • Fields pre-populate with values you specify
  • Visitors can edit the prefilled information
  • Use when: You want to save time but allow corrections

Prefill Type 2 (Locked Fields):

  • Add &prefill=2 to your URL
  • Fields pre-populate and become read-only
  • Visitors cannot modify the prefilled values
  • Use when: You want to ensure specific data (like source tracking) stays consistent

Important: Even locked fields aren't truly secure. Technically savvy users can modify URL parameters or use browser tools to change values. Use this for convenience and tracking, never for security-critical data.

Time: 1 minute


3. Identify Your Form Field Names

Before building prefill URLs, you need to know the exact names of your form fields as they exist in your landing page.

Open your landing page and click Edit with Content Designer.

Click on the Form element on your page to open Form Properties.

Look at each field and note its exact name. Click Edit under each field to see the field label—this is the name you'll use in your URL.

Common standard field names:

  • name - Full name
  • firstname - First name only
  • lastname - Last name only
  • email - Email address
  • phone - Phone number
  • company - Company name

Custom field names vary—write down exactly what you named each field, including capitalization. Field names are case-sensitive.

Time: 3-5 minutes


4. Build a Prefill URL

Start with your landing page's standard URL (the Full Link you get from the Links dropdown).

Add your prefill parameters to the end of the URL using this format:

Basic structure:

https://your-landing-page-url?prefill=1&fieldname=value&fieldname=value

Example - Editable prefill:

https://yourcrm.com/page/webinar-registration?prefill=1&firstname=John&lastname=Smith&email=john@example.com

This URL would:

  • Pre-fill the first name field with "John"
  • Pre-fill the last name field with "Smith"
  • Pre-fill the email field with "john@example.com"
  • Allow the visitor to edit all three fields

Example - Locked prefill:

https://yourcrm.com/page/webinar-registration?prefill=2&name=John+Smith&email=john@example.com&source=Email+Campaign

This URL would:

  • Pre-fill name and email fields
  • Lock those fields so they can't be edited
  • Pre-fill a hidden or visible source field

Key formatting rules:

  • Start parameters with ? after your base URL
  • Separate each parameter with &
  • Use = between field names and values
  • Replace spaces with + signs (or use %20)
  • Field names must match your form exactly (case-sensitive)

Time: 5-10 minutes to construct URL


5. Test Your Prefill URL

Copy your constructed prefill URL and paste it into your browser's address bar.

Press Enter to load the landing page with prefill parameters.

Verify that:

  • The correct fields populate with the values you specified
  • Prefill type 1 allows editing the fields
  • Prefill type 2 locks the fields (try to edit them—you shouldn't be able to)
  • The form still submits successfully with prefilled data

Submit the test form to ensure the prefilled values appear correctly in the contact record in your CRM.

If fields don't prefill:

  • Check that field names match exactly (case-sensitive)
  • Verify you're using the correct prefill type (1 or 2)
  • Confirm the landing page uses Content Designer (not legacy templates)
  • Look for typos in the URL structure

Time: 5 minutes


6. Use Prefilled URLs in Campaigns

Once your prefill URL works correctly, use it in:

Personalized email campaigns: Create unique URLs for each recipient using mail merge to insert their name and email into the URL parameters. This dramatically reduces form friction since they only need to click submit.

Follow-up communications: When following up with known contacts, include prefilled URLs in your messages so they don't need to re-enter information they've already provided.

CRM-triggered automations: Use prefilled URLs in automated workflows or autoresponders where you know recipient information from their contact record.

Event invitations: Pre-fill attendee names in event registration forms sent to confirmed guests.

Track performance by creating separate landing pages or using different source parameters in your prefilled URLs to measure conversion rates.

Time: Ongoing campaign use


7. Understand Hidden Fields

Hidden fields capture information invisibly—they exist on your form but don't display to visitors. Use them to track:

  • Campaign IDs or names
  • Ad platform identifiers
  • Source/medium attribution
  • Custom tracking parameters
  • UTM codes from marketing campaigns

Hidden fields automatically populate when the form submits, adding data to the contact record without requiring visitor input.

Time: 2 minutes to understand


8. Create a Hidden Field

Open your landing page and click Edit with Content Designer.

Click on your Form element to open Form Properties on the right.

Click Add New Field to create a new field.

A new field appears on your form. Click Edit below the new field.

In the Field Editor:

1. Choose the field name - Enter a descriptive internal name like "campaign_source" or "ad_id"

2. Select field type - Choose Text (hidden fields must be text fields)

3. Set the label to %%hidden%% - This exact text (including the %% symbols) tells the system to hide the field from visitors

4. Enter your value in the Placeholder field - Whatever you type here becomes the hidden field's value when the form submits

Example configuration:

  • Field name: campaign_source
  • Field type: Text
  • Label: %%hidden%%
  • Placeholder: Facebook Ad - Q1 2025

Click Save to create the hidden field.

Time: 3-5 minutes per hidden field


9. Verify Hidden Field Behavior

Click Done Editing to exit the Content Designer.

Click the Preview tab to see your landing page as visitors will see it.

The hidden field should be completely invisible on the preview—you won't see it anywhere on the form.

If you still see the field displayed:

  • Verify you typed %%hidden%% exactly (with %% on both sides)
  • Check that there are no extra spaces or characters
  • Confirm you set it as the Label, not the Placeholder

Note: The field will show when you're editing in the Content Designer (so you know it exists), but it's hidden on the preview and public page.

Time: 2 minutes


10. Test Hidden Field Submission

On the Preview tab, fill out your form completely and submit it.

Go to your Contacts database and open the contact record that was just created from your test submission.

Look for the field you configured as hidden—it should contain the value you entered in the Placeholder field.

For example, if you set a hidden field called "campaign_source" with placeholder "Facebook Ad - Q1 2025", the contact record should show "Facebook Ad - Q1 2025" in that field.

This confirms the hidden field captured data correctly without displaying to the visitor.

Delete or clearly mark the test contact after verification.

Time: 3-5 minutes


11. Combine Hidden Fields with Prefilling

You can use hidden fields and URL prefilling together for powerful tracking:

Example combined URL:

https://yourcrm.com/page/registration?prefill=1&name=John+Smith&email=john@example.com

Plus a hidden field on the form with:

  • Label: %%hidden%%
  • Placeholder: Email Campaign - January Newsletter

When John submits the form:

  • His name and email are prefilled (reducing friction)
  • The hidden field captures "Email Campaign - January Newsletter" (tracking the source)
  • You can see in your CRM exactly which email campaign generated this submission

Use different landing pages or different hidden field values for different campaigns to track attribution accurately.

Time: 5 minutes to set up

Questions and Answers

Q: Can visitors see hidden fields if they view the page source?

A: Yes. Hidden fields exist in the page HTML—technically savvy users can view them using browser developer tools. Never use hidden fields for sensitive information or assume they're secure. Use them for tracking and attribution, not data security.


Q: What happens if I prefill a field that doesn't exist on my form?

A: The system ignores prefill parameters that don't match actual field names. Only fields that exist on your form and match the parameter names exactly will populate. Mismatched parameters have no effect.


Q: Can I prefill multiple choice or dropdown fields?

A: The prefilling feature is designed primarily for text fields. Prefilling dropdowns or radio buttons is not reliably supported and may not work as expected.


Q: What's the maximum length for prefilled values in URLs?

A: URLs have practical limits around 2,000 characters depending on browsers. Keep prefilled values concise—full paragraphs won't work. URLs with excessive parameters may get truncated or fail.


Q: Can I use hidden fields to override duplicate handling?

A: No. Hidden fields add data to contact records just like visible fields, but they don't affect the duplicate detection logic. Duplicates are still identified by email address and handled according to your Actions tab settings.


Q: What if someone changes a prefilled value before submitting?

A: If using prefill=1 (editable), visitors can change any prefilled value and the form will submit with their edited information. If using prefill=2 (locked), fields are read-only through the normal interface, but tech-savvy users could still modify them through browser tools or by editing the URL.


Q: Can I prefill hidden fields through the URL?

A: Yes. You can pass values to hidden fields through URL parameters just like visible fields. The field name in the URL must match the hidden field's name exactly.


Q: How do I create unique prefilled URLs for hundreds of contacts?

A: Use your CRM's mail merge or export functionality to generate unique URLs for each contact. Export your contact list with the fields you need, then use a spreadsheet formula to construct custom URLs for each person. Or use your email platform's merge tag features to build dynamic URLs.


Q: Why would I use hidden fields instead of just asking visitors to fill in the information?

A: Hidden fields capture tracking data that visitors don't need to see or shouldn't need to provide—like which ad campaign they came from, internal campaign IDs, or attribution codes. They reduce form friction by not showing unnecessary fields while still capturing important marketing data.


Q: Can I use conditional logic with prefilled or hidden fields?

A: Conditional form logic (showing/hiding fields based on selections) isn't available on landing pages. Prefilled and hidden fields work independently—they don't trigger any conditional behavior.


Q: What happens if I forget to include the prefill=1 or prefill=2 parameter?

A: Without the prefill parameter, the other field parameters in your URL will be ignored. The landing page will display normally with empty form fields. Always include either prefill=1 or prefill=2 for URL prefilling to work.


Q: Can I combine this with the Actions tab automations?

A: Yes. Prefilled and hidden fields work seamlessly with all Actions tab configurations. When the form submits, all the standard automations (workflows, autoresponders, tags, categories) trigger normally using both visible and hidden field data.

Guide Type: How-To Guide

Estimated Time: 30 minutes