Technically, it is possible to send an API request, without the API key parameter or with an invalid API key. In both cases, a QR Code image with a 'preview' watermark will be returned.
QR Codes with the preview watermarks will be unscannable using most QR Code scanning applications.
To get a valid API key, you will need to start an API subscription with Scanova.
If you still have questions, feel free to reach out to us at firstname.lastname@example.org