Billing Data Prefill

Prefilling billing data reduces friction in the checkout process by automatically populating form fields with customer information you already have.

Available Fields

Field	SDK Property	HTML Attribute	Query Parameter
Email	`billingData.email`	`data-fungies-billing-email`	`fngs-customer-email`
First Name	`billingData.firstName`	`data-fungies-billing-first-name`	`fngs-customer-first-name`
Last Name	`billingData.lastName`	`data-fungies-billing-last-name`	`fngs-customer-last-name`
Country	`billingData.country`	`data-fungies-billing-country`	`fngs-customer-country`
State	`billingData.state`	`data-fungies-billing-state`	`fngs-customer-state`
City	`billingData.city`	`data-fungies-billing-city`	`fngs-customer-city`
ZIP Code	`billingData.zipCode`	`data-fungies-billing-zip-code`	`fngs-customer-zip-code`

The legacy customerEmail property and data-fungies-customer-email attribute are still supported but deprecated. Use billingData.email instead.

Usage Examples

JavaScript SDK

Fungies.Checkout.open({
  checkoutUrl: "https://yourstore.fungies.io/checkout-element/abc123",
  settings: { mode: "overlay" },
  billingData: {
    email: "john.doe@example.com",
    firstName: "John",
    lastName: "Doe",
    country: "US",
    state: "CA",
    city: "Los Angeles",
    zipCode: "90001"
  }
});

HTML Data Attributes

<button
  data-fungies-checkout-url="https://yourstore.fungies.io/checkout-element/abc123"
  data-fungies-mode="overlay"
  data-fungies-billing-email="john.doe@example.com"
  data-fungies-billing-first-name="John"
  data-fungies-billing-last-name="Doe"
  data-fungies-billing-country="US"
  data-fungies-billing-state="CA"
  data-fungies-billing-city="Los Angeles"
  data-fungies-billing-zip-code="90001">
  Buy Now
</button>

Query Parameters (Hosted Checkout)

https://yourstore.fungies.io/checkout/offer-id
  ?fngs-customer-email=john.doe@example.com
  &fngs-customer-first-name=John
  &fngs-customer-last-name=Doe
  &fngs-customer-country=US
  &fngs-customer-state=CA
  &fngs-customer-city=Los%20Angeles
  &fngs-customer-zip-code=90001

Remember to URL-encode values that contain special characters (spaces, @, etc.).

Country Codes

The country field accepts ISO 3166-1 alpha-2 country codes:

Code	Country
`US`	United States
`GB`	United Kingdom
`CA`	Canada
`AU`	Australia
`DE`	Germany
`FR`	France
`PL`	Poland
`JP`	Japan
…	Full list

State/Province Codes

For countries that require state/province selection (US, Canada, Australia, etc.), use the appropriate subdivision codes: United States:

CA - California
NY - New York
TX - Texas
etc.

Canada:

ON - Ontario
BC - British Columbia
QC - Quebec
etc.

Field Visibility

Billing fields are only visible in checkout when:

Billing information is enabled in your checkout settings, or
Your Stripe account is based in India (required by regulations)

If billing fields are hidden, the prefilled data will still be stored with the order.

Priority Order

When multiple sources provide billing data, this priority is used:

Query parameters / SDK billingData - Highest priority
Persisted customer data - From previous sessions (local storage)
IP-based detection - Automatic country detection
Default values - Fallback (e.g., United States)

This ensures that explicitly passed billing data always takes precedence over previously saved data.

Additional Query Parameters

Beyond billing data, hosted checkout supports these query parameters:

Parameter	Description
`fngs-quantity`	Product quantity
`fngs-discount-code`	Discount code to apply

Example with Discount

https://yourstore.fungies.io/checkout/offer-id
  ?fngs-customer-email=john@example.com
  &fngs-customer-country=US
  &fngs-discount-code=SAVE20
  &fngs-quantity=2

​Available Fields

​Usage Examples

​JavaScript SDK

​HTML Data Attributes

​Query Parameters (Hosted Checkout)

​Country Codes

​State/Province Codes

​Field Visibility

​Priority Order

​Additional Query Parameters

​Example with Discount

Available Fields

Usage Examples

JavaScript SDK

HTML Data Attributes

Query Parameters (Hosted Checkout)

Country Codes

State/Province Codes

Field Visibility

Priority Order

Additional Query Parameters

Example with Discount