Getting the current URL or simular in WebView

Using Xamarin Forms.

So we are building an commence app. And when our costumer wishes to pay, we open a WebView.

In the WebView we POST the payment portal (paypal etc.) and receive the HTML which we then show in the WebView.
However when the costumer is finished purchasing they are forwarded to a "successUrl", however how is it possible within the app to check if we are being forwarded to this URL and how can we inside the app then react upon this and show another view.

Best regards.