Pre-Fill Forms with URL Parameters

Stop making customers type information you already have. Pre-fill forms with customer data from your CRM, email list, or support system.

How does URL prefilling work?

Quick Answer:
URL prefilling auto-fills form fields by adding parameters to your form link (e.g., formflux.io/f/ABC123?email=user@example.com&name=John+Smith). Works with all embed types, supports simplified field names based on labels, and improves completion rates by 20-30% by reducing customer effort. No coding required, no URL length limits for practical use.

URL Format Breakdown

The basic format is simple. Add a question mark and field names to your form URL:

Regular form link:
https://formflux.io/f/ABC123

Pre-filled form link:
https://formflux.io/f/ABC123?email=john@company.com&name=John+Smith

When someone clicks the second link, the email and name fields are already filled in.

URL Format

The pattern: formflux.io/f/YOUR-FORM-ID?field-name=value

• ? starts the parameters
• field-name matches your form field label (simplified)
• = connects field to value
• + for spaces in values
• & to add multiple fields

Matching Field Names

You have two options:

Option 1: Simplified Field Labels

Convert your field label to lowercase and replace spaces with hyphens.

• Field label: "Full Name" → URL: full-name
• Field label: "Email Address" → URL: email-address
• Field label: "Phone Number" → URL: phone-number

Option 2: Exact Field ID

Use the field ID from your form builder for guaranteed matching.

Real-World Examples

Email Campaign

You're sending a feedback survey to customers. Pre-fill their name and email from your mailing list.

Mailchimp example:
https://formflux.io/f/ABC123?email=|EMAIL|&name=|FNAME| |LNAME|

HubSpot example:
https://formflux.io/f/ABC123?email={{ contact.email }}&name={{ contact.firstname }} {{ contact.lastname }}

Support Ticket

Customer clicks "Contact Support" from your app. Pre-fill their account details.

Link from your app: https://formflux.io/f/ABC123?name=John+Smith&email=john@company.com&account-id=12345

Customer just describes their issue. Everything else is already filled in.

Event Registration

Send calendar invite with registration link. Pre-fill attendee info.

Calendar invite link: https://formflux.io/f/ABC123?attendee-name=John+Smith&company=Acme+Corp

One-click registration with minimal typing required.

CRM Lead Qualification

Sales team sends qualification forms. CRM data auto-fills.

• Salesforce example:
  https://formflux.io/f/ABC123?email={!Contact.Email}&company={!Account.Name}

• Pipedrive example:
  https://formflux.io/f/ABC123?name={{person.name}}&email={{person.email}}

Product Order Form

Customer clicks "Buy Now" on product page. Form remembers what they clicked.

Product page button links to:

https://formflux.io/f/ABC123?product=Widget+Pro&variant=Blue+Large&quantity=1

Order form shows their product choice. They just enter shipping info.

Email Platform Examples

• Mailchimp:
  https://formflux.io/f/ABC123?email=|EMAIL|&name=|FNAME|
• SendGrid:
  https://formflux.io/f/ABC123?email={{email}}&name={{first_name}}
• ActiveCampaign:
  https://formflux.io/f/ABC123?email=%EMAIL%&name=%FIRSTNAME%
• ConvertKit:
  https://formflux.io/f/ABC123?email={{subscriber.email_address}}&name={{subscriber.first_name}}

Using with Embedded Forms

Iframe:

Add parameters to the iframe src URL:

<iframe src="https://formflux.io/f/ABC123?email=customer@example.com" width="100%" height="600"></iframe>

JavaScript Widget:

Use the prefill config option instead:

new FormWidget({ formId: 'ABC123', type: 'inline', prefill: { 'email': 'customer@example.com', 'name': 'Jane Smith' } })

Common Mistakes

Spaces in URLs:

Wrong: ?name=John Smith

Right: ?name=John+Smith

Wrong Field Names:

Wrong: ?fullname=John (field is actually "full-name")

Right: ?full-name=John

Sensitive Data:

Never prefill passwords, credit cards, or private information in URLs. URLs appear in browser history and server logs.

URL Encoding

Some characters need special encoding:

• Space: Use + or %20
• Ampersand: Use %26
• Equals: Use %3D
• Hash: Use %23

Most email platforms handle this automatically with their merge tags.

Testing

Before sending to customers:

1. Create a test link with sample data

2. Click it to see the form

3. Verify fields prefill correctly

4. Submit a test response

5. Check the response in your dashboard

Test link example:

https://formflux.io/f/ABC123?email=test@example.com&name=Test+User

Troubleshooting

Fields not prefilling:

Check the parameter name matches your field label (lowercase with hyphens). Try using the exact field ID from the form builder.

Some fields work, others don't:

The working fields match correctly. For non-working fields, verify the exact field label and convert to lowercase with hyphens.

URL too long:

Prefill only essential fields. Keep URLs under 2000 characters.

Security Note

Only prefill data that's safe to appear in an email link. URLs are visible in browser history and server logs.

Safe: Name, email, company, account ID, product selections

Never: Passwords, credit cards, social security numbers, health data