RdapClient is a .Net client for Registration Data Access Protocol (RDAP).
https://rdap.darkpeaklabs.com/
using RdapClient service = new RdapClient();
var result = await service.DomainLookupAsync(new Uri("https://rdap.verisign.com/com/v1/"), "example.com");
The RDAP bootstrap classes provide programmatic way to obtain RDAP lookup service URLs for various RDAP objects.
var bootstrap = new RdapDnsBootstrap();
var serviceUri = await bootstrap.FindServiceUrlAsync("example.com");
using RdapClient service = new RdapClient();
var result = await service.DomainLookupAsync(serviceUri, "example.com");