URL Prefill Parameters

Givebutter Widgets support URL parameters that automatically pre-fill form fields when donors visit your page. This creates a personalized experience and reduces friction in the donation process.

How It Works

When a user visits a page with a Givebutter Widget, URL parameters are automatically detected and used to pre-fill form fields. This works with both button widgets (popup forms) and inline form widgets.

User Clicks Custom Link

Donor clicks a personalized link from your email, SMS, or other channel

Parameters Detected

Widget library reads URL parameters from the page

Form Pre-filled

Donation form opens with information already filled in

Faster Checkout

Donor completes their gift with fewer steps

Supported Parameters

Donor Information

Pre-fill contact information to create a personalized experience:

Parameter	Description	Example
`gb_first_name`	Donor’s first name	`?gb_first_name=Sarah`
`gb_last_name`	Donor’s last name	`?gb_last_name=Johnson`
`gb_email`	Donor’s email address	`[email protected]`
`gb_phone`	Donor’s phone number	`?gb_phone=5551234567`
`gb_company`	Company or organization name	`?gb_company=Acme+Corporation`

Donation Details

Control donation amount and preferences:

Parameter	Description	Example
`gb_amount`	Preset donation amount (in cents)	`?gb_amount=5000` ($50.00)
`gb_recurring`	Set as recurring donation	`?gb_recurring=true`
`gb_frequency`	Recurring frequency	`?gb_frequency=monthly`
`gb_fund`	Specific fund designation	`?gb_fund=scholarship`
`gb_quantity`	Number of items/tickets	`?gb_quantity=2`

Donation Frequency Options

When using gb_frequency, supported values:

weekly - Donate every week
monthly - Donate every month (most common)
quarterly - Donate every 3 months
yearly - Donate once per year

Address Information

Pre-fill address fields for events, merchandise, or tax receipts:

Parameter	Description	Example
`gb_address_line1`	Street address	`?gb_address_line1=123+Main+St`
`gb_address_line2`	Apartment, suite, etc	`?gb_address_line2=Apt+4B`
`gb_address_city`	City	`?gb_address_city=Portland`
`gb_address_state`	State/Province	`?gb_address_state=OR`
`gb_address_zip`	Postal code	`?gb_address_zip=97201`
`gb_address_country`	Country code	`?gb_address_country=US`

URL Encoding

When building URLs with parameters, ensure special characters are properly encoded:

Spaces: Use + or %20
@ symbol: Use %40
Ampersand: Use %26 (in values, not between parameters)

https://yoursite.org/[email protected]&gb_company=Smith & Sons

Examples

Basic Donor Personalization

Pre-fill name and email for a personalized experience:

https://yoursite.org/donate?gb_first_name=John&gb_last_name=Smith&gb_email=john%40example.com

Preset Donation Amount

Direct donors to a specific giving level:

https://yoursite.org/donate?gb_amount=10000

Important: Amounts are in cents. So $100.00 = gb_amount=10000

Monthly Giving Campaign

Create links for recurring donation campaigns:

https://yoursite.org/donate?gb_amount=2500&gb_recurring=true&gb_frequency=monthly

This creates a $25/month recurring donation.

Event Registration Link

Pre-fill attendee information and ticket quantity:

https://yoursite.org/event?gb_first_name=Sarah&gb_last_name=Johnson&gb_email=sarah%40example.com&gb_quantity=2

Full Example with All Fields

A complete personalized donation link:

https://yoursite.org/donate?gb_first_name=Michael&gb_last_name=Chen&gb_email=michael%40example.com&gb_phone=5551234567&gb_amount=5000&gb_recurring=true&gb_frequency=monthly&gb_fund=education

Use Cases

Email Personalization
Text/SMS Campaigns
Direct Mail
Member Renewals
Fundraiser Pages

Use your email marketing platform’s merge tags to create personalized links:

<!-- Mailchimp example -->
<a href="https://yoursite.org/donate?gb_first_name=*|FNAME|*&gb_last_name=*|LNAME|*&gb_email=*|EMAIL|*">
  Donate Now
</a>

<!-- Constant Contact example -->
<a href="https://yoursite.org/donate?gb_first_name={First Name}&gb_last_name={Last Name}&gb_email={Email Address}">
  Make Your Gift
</a>

Benefits:

Reduces form friction
Increases conversion rates
Creates personal touch

Create short, trackable links for SMS:

Hi Sarah! Support our Spring Campaign: https://give.org/spring?gb_first_name=Sarah&gb_amount=2500

(Tip: Use a URL shortener like bit.ly)

Best Practices:

Keep URLs short with shorteners
Pre-fill name and suggested amount
Include campaign in URL for tracking

Add personalized QR codes to printed materials:

Generate unique QR codes for each recipient:
https://yoursite.org/donate?gb_first_name=John&gb_last_name=Smith&utm_source=direct-mail&utm_campaign=spring-2026&gb_amount=10000

Benefits:

Track offline campaign success
Personalize the digital experience
Suggest giving level based on donor history

Send renewal reminders with pre-filled information:

https://yoursite.org/renew?gb_first_name=Jane&gb_last_name=Doe&gb_email=jane%40example.com&gb_amount=15000&gb_recurring=true&gb_frequency=yearly

Benefits:

One-click renewal process
Maintain recurring giving
Reduce manual data entry

Help peer-to-peer fundraisers share personalized links:

https://yoursite.org/team-sarah?gb_fund=team-sarah&utm_source=peer-fundraiser&utm_campaign=sarah-birthday

Benefits:

Track individual fundraiser performance
Direct donations to specific funds
Encourage social sharing

Combining with UTM Parameters

Prefill parameters work seamlessly with UTM tracking parameters:

https://yoursite.org/donate?utm_source=newsletter&utm_medium=email&utm_campaign=spring-2026&gb_first_name=Sarah&gb_email=sarah%40example.com&gb_amount=5000

This link will:

Track the donation source (newsletter, email campaign)
Pre-fill donor information (Sarah, [email protected])
Suggest a $50 donation

Building URLs Programmatically

JavaScript Example

function buildDonationUrl(baseUrl, params) {
  const url = new URL(baseUrl);

  // Add prefill parameters
  if (params.firstName) url.searchParams.set('gb_first_name', params.firstName);
  if (params.lastName) url.searchParams.set('gb_last_name', params.lastName);
  if (params.email) url.searchParams.set('gb_email', params.email);
  if (params.amount) url.searchParams.set('gb_amount', params.amount);

  // Add UTM parameters
  if (params.utmSource) url.searchParams.set('utm_source', params.utmSource);
  if (params.utmMedium) url.searchParams.set('utm_medium', params.utmMedium);
  if (params.utmCampaign) url.searchParams.set('utm_campaign', params.utmCampaign);

  return url.toString();
}

// Usage
const link = buildDonationUrl('https://yoursite.org/donate', {
  firstName: 'John',
  lastName: 'Smith',
  email: '[email protected]',
  amount: 5000, // $50.00
  utmSource: 'email',
  utmMedium: 'newsletter',
  utmCampaign: 'spring-2026',
});

console.log(link);
// https://yoursite.org/donate?gb_first_name=John&gb_last_name=Smith&gb_email=john%40example.com&gb_amount=5000&utm_source=email&utm_medium=newsletter&utm_campaign=spring-2026

Python Example

from urllib.parse import urlencode

def build_donation_url(base_url, params):
    query_params = {}

    # Add prefill parameters
    if 'first_name' in params:
        query_params['gb_first_name'] = params['first_name']
    if 'last_name' in params:
        query_params['gb_last_name'] = params['last_name']
    if 'email' in params:
        query_params['gb_email'] = params['email']
    if 'amount' in params:
        query_params['gb_amount'] = params['amount']

    # Add UTM parameters
    if 'utm_source' in params:
        query_params['utm_source'] = params['utm_source']

    return f"{base_url}?{urlencode(query_params)}"

# Usage
link = build_donation_url('https://yoursite.org/donate', {
    'first_name': 'Sarah',
    'last_name': 'Johnson',
    'email': '[email protected]',
    'amount': 10000,  # $100.00
    'utm_source': 'email'
})

print(link)

Best Practices

Respect Privacy

Only pre-fill information you legitimately have:

Use data from your CRM or email platform
Don’t pre-fill sensitive information unless secure
Respect GDPR and privacy regulations
Allow donors to modify pre-filled fields

Test Your Links

Always test personalized links before sending: - Click the link yourself - Verify all fields pre-fill correctly - Check for URL encoding issues - Test on mobile devices - Confirm donation completes successfully

Use URL Shorteners

Long URLs with many parameters can be unwieldy: - Use bit.ly, TinyURL, or custom shorteners - Track click-through rates - Make links more shareable - Better for SMS and social media

Set Reasonable Defaults

When suggesting donation amounts: - Base on donor history if available - Use campaign-appropriate levels - Don’t set amounts too high (can deter donors) - Consider offering multiple pre-set links

Combine with Personalization

Create a complete personalized experience:

Pre-fill form + personalized landing page copy
Match suggested amount to donor capacity
Reference past giving or engagement
Use consistent messaging across channels

Troubleshooting

Fields not pre-filling? Ensure URL parameters are properly encoded and the Widgets library is installed on your page.

Parameters not working

Common issues:

Missing gb_ prefix on parameter names
URL encoding problems (spaces, special characters)
Widgets library not loaded on page
Parameters stripped by redirects
Wrong parameter names or values

Solution: Copy example URLs from this page and modify carefully.

Amount displays incorrectly

The gb_amount parameter uses cents, not dollars:

✅ Correct: gb_amount=5000 for $50.00
❌ Incorrect: gb_amount=50 (this is $0.50)

Always multiply dollar amounts by 100.

Email not encoding properly

Email addresses must have the @ symbol encoded:

✅ Correct: gb_email=user%40example.com
❌ Incorrect: [email protected]

Use %40 instead of @ in URLs.

Recurring donation not working

Both parameters are required for recurring:

?gb_recurring=true&gb_frequency=monthly

Don’t forget to set both gb_recurring AND gb_frequency.

Security Considerations

Important: Pre-filled values are suggestions only. Donors can always modify any pre-filled field before submitting their donation.

Never pre-fill payment information (card numbers, CVV, etc.)
Don’t include sensitive personal information in URLs
URLs may be logged by servers, analytics tools, and browser history
Use HTTPS for all donation pages
Consider using POST requests for highly sensitive scenarios

Link Builder

Interactive tool for building custom links (coming soon)

Analytics

Add UTM parameters for campaign tracking

Button Widget

Works with all button widgets

Form Widget

Works with all form widgets

Overview

Widget Types

Integrations

Website Builders

Advanced

URL Prefill Parameters

How It Works

Supported Parameters

Donor Information

Donation Details

Donation Frequency Options

Address Information

URL Encoding

Examples

Basic Donor Personalization

Preset Donation Amount

Monthly Giving Campaign

Event Registration Link

Full Example with All Fields

Use Cases

Combining with UTM Parameters

Building URLs Programmatically

JavaScript Example

Python Example

Best Practices

Troubleshooting

Security Considerations

Link Builder

Analytics

Button Widget

Form Widget

Overview

Widget Types

Integrations

Website Builders

Advanced

​How It Works

​Supported Parameters

​Donor Information

​Donation Details

​Donation Frequency Options

​Address Information

​URL Encoding

​Examples

​Basic Donor Personalization

​Preset Donation Amount

​Monthly Giving Campaign

​Event Registration Link

​Full Example with All Fields

​Use Cases

​Combining with UTM Parameters

​Building URLs Programmatically

​JavaScript Example

​Python Example

​Best Practices

​Troubleshooting

​Security Considerations

​Related Resources

Link Builder

Analytics

Button Widget

Form Widget

How It Works

Supported Parameters

Donor Information

Donation Details

Donation Frequency Options

Address Information

URL Encoding

Examples

Basic Donor Personalization

Preset Donation Amount

Monthly Giving Campaign

Event Registration Link

Full Example with All Fields

Use Cases

Combining with UTM Parameters

Building URLs Programmatically

JavaScript Example

Python Example

Best Practices

Troubleshooting

Security Considerations

Related Resources