ipcheckudp.dynu.com is a subdomain of the well-known dynamic DNS provider Dynu, and it appears to host a simple IP-checking tool. For a service like this, you don’t usually need deep company background or customer support — users just want the tool to work. And on that front, the signals are clean: a valid SSL certificate, no blacklist history, and both a privacy policy and terms of service are posted.
Still, there are a couple of things to keep in mind. There’s no contact information on the page, and the subdomain has no presence in the Wayback Machine — meaning there’s no public record of how long it’s been around. That’s not uncommon for a small side project, but it does mean you have less evidence to lean on if something goes wrong.
If you’re using this to check your own IP or UDP connectivity, the lack of a big trust history probably isn't a dealbreaker. Just know that the site doesn’t provide a direct way to reach anyone, and it hasn’t built up a visible track record. That’s typical for a no-frills utility, and there’s nothing here that screams scam.