program JSONPostExample;

{$APPTYPE CONSOLE}

uses
  IdHTTP, IdGlobal, SysUtils, Classes;

var
  HTTP: TIdHTTP;
  RequestBody: TStream;
  ResponseBody: string;
begin
  HTTP := TIdHTTP.Create;
  try
    try
      RequestBody := TStringStream.Create('{"code":42}',
        TEncoding.UTF8);
      try
        HTTP.Request.Accept := 'application/json';
        HTTP.Request.ContentType := 'application/json';
        ResponseBody := HTTP.Post('https://httpbin.org/post',
          RequestBody);
        WriteLn(ResponseBody);
        WriteLn(HTTP.ResponseText);
      finally
        RequestBody.Free;
      end;
    except
      on E: EIdHTTPProtocolException do
      begin
        WriteLn(E.Message);
        WriteLn(E.ErrorMessage);
      end;
      on E: Exception do
      begin
        WriteLn(E.Message);
      end;
    end;
  finally
    HTTP.Free;
  end;
  ReadLn;
end.