What Happened to icloud.com/activationlock

I noticed as of yesterday that icloud.com/activationlock was having errors. As of today that page now says that it can not be found.

Is there a new method of checking the IMEI / Serial of a device online? Without this tool how is one to know that they will be able activate a used device that they could potentially be purchasing via eBay, Craigslist, etc...

Thank you.