# Checkout URL Parameters (/en/paylinks/checkout-parameters)



Overview [#overview]

You can add query parameters to a payment link URL to prefill the checkout form and
attach your own identifiers. The hosted checkout reads these parameters and includes
them when the payment (invoice) is created, so they flow through to your webhooks.

This is the recommended way to tie a payment back to a user or order in your system:
pass `clientReferenceId`, and it is returned on payment and invoice webhook events as
`customer.clientReferenceId`.

Usage [#usage]

Append parameters to the payment link URL:

```
https://pay.yolfi.com/{paylink-id}?clientReferenceId=user_123&email=customer@example.com
```

They also work together with the [language prefix](/en/paylinks/language):

```
https://pay.yolfi.com/{language}/{paylink-id}?clientReferenceId=user_123
```

Supported Parameters [#supported-parameters]

| Parameter           | Description                                                                                              |
| :------------------ | :------------------------------------------------------------------------------------------------------- |
| `clientReferenceId` | Your internal customer or order reference. Returned as `customer.clientReferenceId` in webhook payloads. |
| `email`             | Prefills the customer email.                                                                             |
| `name`              | Prefills the customer name.                                                                              |
| `phone`             | Prefills the customer phone.                                                                             |
| `dob`               | Prefills the customer date of birth.                                                                     |
| `address`           | Prefills the customer address.                                                                           |
| `subscriptionId`    | Associates the payment with an existing subscription.                                                    |
| `metadata[KEY]`     | Adds a string metadata field to the invoice and signed webhook events.                                   |

All parameters are optional. Values must be URL-encoded (for example, encode `@` in an
email address as `%40`).

Metadata keys may contain letters, numbers, `_`, and `-`. For example:

```text
https://pay.yolfi.com/{paylink-id}?metadata[order_id]=order_123&metadata[campaign]=summer
```

Metadata supplied by the browser is attribution context, not authentication. A Paylink's
server-controlled `paymentMetadata` has priority over query metadata and is the appropriate
place for routing values that buyers must not be able to change.

How it reaches your webhooks [#how-it-reaches-your-webhooks]

When the customer completes checkout, these values are attached to the created invoice's
customer and delivered in your webhook events (see [Webhook Details](/en/webhooks/webhook-details)).
Use `clientReferenceId` (or `email`) to match the payment to a customer in your system.

> **Note:** `clientReferenceId` is included on invoice and payment events (for example
> `payment.confirmed`). Metadata remains scoped to the payment that created the event; it is not
> copied from the first checkout onto later subscription renewals.

Setting it server-side [#setting-it-server-side]

For dynamic orders, create an authenticated [API Checkout Session](/en/checkout) and set
`clientReferenceId`, `merchantOrderId`, and trusted metadata on that session. The browser should
not call the public payment endpoint directly with a price.

Redirect after payment [#redirect-after-payment]

Post-payment redirects are configured on the Payment Link; they are not checkout URL parameters.
See [After a Payment](/en/paylinks/after-payment) to configure a basic redirect or optionally pass
the Checkout Session ID to your return page.