POST Ratificacion/Login in https://apiadv.sintia.com.ar/Help/Api/POST-Ratificacion-Login

func RatificacionLogin() {
    url := "https://apiadv.sintia.com.ar/Ratificacion/Login"

    payload := strings.NewReader("{\n\t\"Username\":\"XXXXXX\",\n\t\"Password\":\"XXXXXXX\"\n}")

    req, _ := http.NewRequest("POST", url, payload)

    req.Header.Add("content-type", "application/json")
    req.Header.Add("cache-control", "no-cache")

    res, _ := http.DefaultClient.Do(req)

    defer res.Body.Close()
    body, _ := ioutil.ReadAll(res.Body)

    fmt.Println(res)
    fmt.Println(string(body))
}