Where can I find the PSD2 API test data?
The test data for our PSD2 APIs (Account Information API, Card-Account Information API, Payment Initiation API and Confirmation of Funds API) is located in our Technical Guidelines, at the bottom of the page in a section called Sandbox test data
When I created a new test application, I received the ClientID but why did I not get the Client Secret?
You only need the ClientId for testing in our Sandbox environment, the Client Secret is not needed. When you go Live, you also need a valid eIDAS certificate (QWAC) from a Qualified Trust Service Provider (QTSP). To read more about this, check out our page for Live Data Enrollment