By default, we pass an encrypted URL parameter to the default Thank You page generated by us that is then decrypted and used by the Thank You page to show Session details.
When using your own Thank You pages, the encrypted URL parameter will still be present and will be passed along, and you can choose to NOT have this URL parameter encrypted, and instead pass in full registrant data, however this can cause certain tracking systems like Google Analytics to throw errors, as they prohibit personally identifiable data to be passed like this without encryption.
If you are looking to use the Registrant data in your Thank You pages either with our widgets or without, you will have to use the decryption script we provide in your Thank You pages.