Easy to use, tested reCaptcha library. Allows to check send data against reCaptcha service. There are other libs to do this, but my returns errors n RecaptchaResponse object so You know what went wrong ;).
recaptcha := gorecaptcha.NewRecaptcha("recaptcha private key")
captchaResponse, err := recaptcha.Verify(
ip,
challenge_from_request_form,
response_from_request_form,
)
if err != nil {
// error (http request error for example)
fmt.Println(err)
}
fmt.Println(captchaResponse.Status) // true or false
fmt.Println(captchaResponse.Err) // actual reason if false