Make Test Calls
After you set up your sandbox accounts and get NVP/SOAP API test credentials, you can make PayPal requests to the sandbox environment.
The following cURL command makes an Express Checkout call to the sandbox.
Execute the request from the command line by replacing the credentials in the command with those from your sandbox business account.
Remove the line breaks.
curl https://api-3t.sandbox.paypal.com/nvp \ -s \ --insecure \ -d USER=YourUserID \ -d PWD=YourPassword \ -d SIGNATURE=YourSignature \ -d METHOD=SetExpressCheckout \ -d VERSION=98 \ -d PAYMENTREQUEST_0_AMT=10 \ -d PAYMENTREQUEST_0_CURRENCYCODE=USD \ -d PAYMENTREQUEST_0_PAYMENTACTION=SALE \ -d cancelUrl=https://example.com/cancel \ -d returnUrl=https://example.com/success
View transaction notifications
During transaction processing, PayPal sends various notifications to the accounts involved in the transaction. Depending on the process flow, notifications can be sent to both the buyer (sender) and merchant (receiver) accounts.
Just like the live site, the sandbox sends notifications for transaction events. However, sandbox-generated email notifications are never sent from outside the sandbox environment.
Instead, all sandbox notifications are sent to the Notifications page of the sandbox account.
Review account notifications through the either:
The sandbox test site by using your sandbox account credentials.
The account's Notifications page, as shown in this figure.
To view the email associated with an account on the test site, log in to the site with the email and password that are associated with the sandbox account.
After you debug your application, move your code to production. To do so, update your PayPal requests so that they address the live environment and update the endpoints and authentication credentials in your API requests.
In addition, if you use any of the Adaptive APIs, you must supply the App ID that PayPal issues after you submit your application for review.
To move your app from test to live, see Go Live with Your App.