It looks like they're using an OCR API such as MSFT's or Google's. I've tried using them in the past, unfortunately these apis are the not useful for a limited set of specific tasks. They rarely worked for more general tasks of the form "take image taken from phone, convert to text" at least not accurately especially from handwritten text
Great app for limited purposes, wish the OCR engine worked better, but in general its useful for storing things like SN or ISBN numbers