program HelloWorldWebServerX3;
 
//{$APPTYPE CONSOLE minimal -extend auto IP Hoster}
//#sign: max: MAXBOX8: 15/01/2017 15:17:48 
//uses SysUtils, IdContext, IdCustomHTTPServer, IdHTTPServer;
 
procedure HTTPServerCommandGet(AContext: TIdPeerThread;
              ARequestInfo: TIdHTTPRequestInfo; ARespInfo: TIdHTTPResponseInfo);
begin
  ARespInfo.ResponseNo:= 200;
  ARespInfo.ContentType:= 'text/plain';
  ARespInfo.ContentText:= 'Hi IBZ TimeServe at: '
                                  +DateTimeToInternetStr(Now,true);
end;
 
begin   //@main
  //TWebServerCreate;
  with TIdHTTPServer.Create(Nil) do begin
    sr:= GetIPfromHost(getHostName)  //'172.16.10.80';
    Bindings.Add.IP:= sr; 
    Bindings.Add.Port:= 8080;
    OnCommandGet:= @HTTPServerCommandGet;
    Active:= True;
    try
      Writeln('Hello world/Web server start at: '+sr);
      ShowMessageBig('maXbox Hello WorldWeb server at: '+sr+#1310+
                          '  Press OK to quit webserver!'+#13);
    finally
      writeln('SocketServer stop: '+timetoStr(now)); //TWebServerDestroy;
      Active:= False;
      Free;
    end;
  end;
End.


ref:
  https://rosettacode.org/wiki/Hello_world/Web_server#Delphi
  add bindings & contenttype for more convention

Doc:
   Function DateTimeToInternetStr( const Value : TDateTime; const AIsGMT : Boolean) : String
   Function GetIPAddress( const HostName : string) : string
   Function GetIP( const HostName : string) : string
   Function GetIPHostByName(const AComputerName: String): String;
   function GetIPFromHost(const HostName: string): string;

   HTTPServer1.Bindings.Add.IP := '127.0.0.1';
   HTTPServer1.Bindings.Add.Port := 50001;
   
  writeln(GetIPAddress(getHostName));
  writeln(GetIP(getHostName));
  writeln(GetIPHostByName(gethostname));
  writeln(GetIPfromhost(gethostname));

This is a common newbie mistake. You are creating two bindings, one bound to 127.0.0.1:DefaultPort, and one bound to 0.0.0.0:50001. You need one binding instead, that is bound to 127.0.0.1:50001 instead.

with HTTPServer1.Bindings.Add do begin
  IP := '127.0.0.1';
  Port := 50001;
end;

call example:

procedure TDataFormbtnHTTPSendGetClick(Sender: TObject);
var
  HTTPClient : TIdHTTP;
  responseStream : TMemoryStream;
begin
  HTTPClient := TIdHTTP.Create(Nil);
  responseStream := TMemoryStream.Create;
  try
    try
      HTTPClient.Get1('http://127.0.0.1:8080', responseStream);
      responseStream.Seek(0, soFromBeginning);
      SetLength(Sr, responseStream.Size);
      responseStream.Read(Sr, responseStream.Size);
      writeln('response: '+sr)
      //writeln(': '+streamtoString3(responseStream))
    except 
      //on e : Exception do begin
      showmessage('Could not send get request to localhost, port 8080');
    end;
    //end;
  finally
    //FreeAndNil(HTTPClient);
    HTTPClient.Free;
    HTTPClient:= Nil;
    responseStream.Free;
  end;
end;


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