WebTraceCheck
When a registry offers no RDAP service your browser can reach, WebTraceCheck's free DNS & domain lookup is another way to check the name. There is also an IP lookup, and a plain-text or JSON IP API for scripts.
Its disposable cloud browser (Brave, Chrome, Edge, Firefox or Chromium on an isolated Linux desktop, deleted after each session) lets you open a suspicious domain you just looked up without loading it on your own machine.
Try WebTraceCheck