package main import ( "crypto/tls" "log" "net/http" "net/url" ) func main() { data := url.Values{ "Firstname": {"Peter"}, "Lastname": {"Lustig"}, "DatenschutzAkzeptiert": {"true"}, "Datum": {"2020-10-12"}, "Schulungscode": {"GO.EINF"}, "Email": {"info@source-fellows.com"}, } //disable TLS check for local tests tlsConfig := &tls.Config{} tlsConfig.InsecureSkipVerify = true http.DefaultClient.Transport = &http.Transport{TLSClientConfig: tlsConfig} res, err := http.PostForm("https://localhost:8443/registrierung", data) if err != nil { panic(err) } log.Println(res.Status) }