# On Demand

The available parameters are:

* **chain** *(string)* - chain used for the payment
* **planId** *(string)* - if od the plan
* **callbackSuccess** *(string)* - redirect url after success (*optional*)
* **callbackError** *(string)* - redirect url after failure (*optional*)
* **extra** *(string)* - json object containing extra parameters that will be sent to webhook (*optional*)

The following data will be appended to the `callbackSuccess` url as query parameters:

* **user** *(string)* - address of the user who completed the payment
* **transactionHash** *(string)* - hash of the transaction

### **Example button**

```markup
<form action="https://checkout.8pay.network/" method="POST">
    <input type="hidden" name="type" value="on_demand">
    <input type="hidden" name="chain" value="bsc">
    <input type="hidden" name="planId" value="0x57b2059e526841b3dfd964144513359c9fcfd6d91040b6c47f589c1e032b6bf7">
    <input type="hidden" name="extra[banner]" value="BR69">
    <input type="hidden" name="extra[traffic]" value="facebook">
    <input type="hidden" name="callbackSuccess" value="https://www.google.com/">
    <input type="hidden" name="callbackError" value="https://www.google.com/">
    <input type="image" src="https://cdn.8pay.network/img/buttons/pay_in_crypto_blue.png" border="0" name="submit" alt="8PAY">
</form>
```