dotnet add package keycloak.admin.client --version 1.0.0

// add in ConfigureService for Asp.Net Core apps
services.AddKeycloakAdminClient(options =>
{
    options.Address  = new Uri("http://localhost:8080/auth/");
    options.Realm    = "master";
    options.Username = "username";
    options.Password = "pasword";
    options.ClientId = "admin-cli";
});

// inject the client 
public SomeController(IKeycloakClient keycloakClient)
{
    _keycloakClient = keycloakClient
}

// or manually create
_keycloakClient = new KeycloakClient(options);

// create client
var clientsResource = _keycloakClient
    .Realms().Id(realmName)
    .Clients();

var client = new Client
{
    ClientId = "app-client",
    Name = "App Client",
    Enabled = true,
    StandardFlowEnabled = true,
    DirectAccessGrantsEnabled = true,
    RedirectUris = new[] {"*"},
    WebOrigins = new[] {"http://localhost:5000"} // this is the app that integrates with the keycloak
};

var clientCreated = await clientsResource.CreateAsync(client);