The PayPal Sandbox is a self-contained environment within which you can prototype and test your PayPal applications. You can make any PayPal transaction just as if you were using live PayPal, except no real money is transferred. To access the Sandbox, you need to have a PayPal Developer Central account. Once you sign into Developer Central, you can access the Sandbox and create test merchant and buyer accounts.

If you don't have these accounts, follow the instructions here: PayPal Sandbox User Guide. Once you have some test accounts and API credentials, enter them above to begin testing.

The credentials you enter above are not permanently stored; they are kept only in Session State and are cleared as soon as you close your browser or after an inactivity timeout. Update the associated properties in the Web.Config file to store your credentials permanently.