You can obtain user data using the JWT token with the Piano PHP SDK and the mobile SDK. Individual SDK libraries are available here.
The JWT is stored in the __utp cookie. In the browser, read __utp from document.cookie and decode its payload (base64) as in the example below:
atob(utpCookieValue.split('.' )[1]);
This returns the JWT claims as a JavaScript object.
In PHP, read the cookie from $_COOKIE['__utp']. First-party cookies are sent with backend requests.
For the mobile SDK, decrypt the JWT to obtain the user details.