---
title: applicationData
framework: applepayontheweb
role: symbol
role_heading: Instance Property
path: applepayontheweb/applepayrequest/applicationdata
---

# applicationData

A Base64-encoded string used to contain your application-specific data.

## Declaration

```data
DOMString applicationData;
```

## Discussion

Discussion Use this property to contain additional data as may be appropriate for your website. For example, the application data may be a shopping cart identifier or an order number that your backend system needs to identify this transaction. You’re responsible for sending the full application data to your server, if needed. important: If you use RegisterMerchantRequest in the Apple Pay Web Merchant Registration API to register merchants, you must include the merchant domain in applicationData. The payment service provider can use the domain in applicationData to ensure they know which merchant the payment token is for. The payment service provider uses the value in applicationData in a step necessary to validate the payment data. For more information, see Payment token format reference. The applicationData string must be a valid Base64-encoded string; otherwise, the system ignores it.