A web version of Nmap available on a website, where one just need to enter the target IP/website address and that website will do a free scan against your target. Free scanning process, is not verifying that one who requesting a scan against website.com, either he actually owns this website or not! Free and paid scan, scanplanner will scan your website regularly. Whereas the Free scanning option is available on website as a demo for new users. Unauthorized Port Scanning a Crime if one is scanning someone else server without authorization and it would be considered as an attempt to hack or find loopholes, in that case Yes, Its a Crime!
Source: https://thehackernews.com/2012/12/hackers-abusing-online-nmap-port.html