It used to be relatively easy to find a domain's owner by looking up the WHOIS information. We got a few of our early clients this way because usually a domain was registered by the company's founder and they'd have their personal email and cell phone number listed. Not many people seemed to know of this 'trick'!
Now, you are lucky if you get anything 1 out of every 100 times. So in a post GDPR world, how do you get information about a domain's owner?