Creating a client session generates a client token: a temporary key used to initialize Universal Checkout and authenticate it against your account.
Universal Checkout automatically retrieves all the settings from the client session and the Dashboard to configure the payment methods and the checkout experience.
The amount, currencyCode and orderId are required to create a payment. If you plan to create a payment using only a paymentMethodToken, remember to pass these fields on your client session request.
Client tokens expire after 24 hours.
Click Try It! to start a request and see the response here!