Mojolicious::Plugin::ReCAPTCHAv2 - use Googles "No CAPTCHA reCAPCTHA" (reCAPTCHA v2) service in Mojolicious apps


version 0.4


    use Mojolicious::Plugin::ReCAPTCHAv2;

    sub startup {
        my $self = shift;

        $self->plugin('ReCAPTCHAv2', {
            sitekey       => 'site-key-embedded-in-public-html',                 # required
            secret        => 'key-used-in-internal-verification-requests',       # required
            # api_timeout => 10,                                                 # optional
            # api_url     => '',  # optional
            # size        => 'normal',                                           # optional
            # tabindex    => 0,                                                  # optional
            # theme       => 'light',                                            # optional
            # type        => 'image',                                            # optional

    # later

    # assembling website:
    $app->stash( captcha => $app->recaptcha_get_html );
    # now use stashed value in your HTML template, i.e.: <form..>...<% $captcha %>...</form>

    # on incoming request
    if ( $app->recaptcha_verify ) {
        # success: probably human
    else {
        # fail: probably bot, but may also be a
        # processing error

        if ( my $err = $app->recaptcha_get_errors ) {
            # processing failed, inspect error codes
            foreach my $e ( @{$err} ) {
        else {
            # bot


Mojolicious::Plugin::ReCAPTCHAv2 allows you to protect your site against automated interaction by (potentially malicious) robots.

This is accomplished by injecting a extra javascript widget in your forms that requires human interaction. The interaction is evaluated on a server (via AJAX) and a dynamic parameter is injected in your form. When your users submit your form to your server you receive that parameter and can verify it by sending it to the captcha servers in the background. You should then stop further processing of the request you received if the captcha did not validate.

Please note that this module currently does not support some advanced usage models for the captcha like explicit rendering and AJAX callbacks. Therefore a few options listed in the official Google docs are not listed above. If you would like to see support for this kind of functionality, please get in touch with the author / maintainer of this module.

For a general overview of what a Captcha is and how the Google "No Captcha" reCaptcha (v2) service works, please refer to the official documentation.


The following params can be provided to the plugin on registration:


sitekey and secret are required parameters, while all others are optional. The default values for the optional configuration params are shown in the synopsis.

For the meaning of these please refer to


Mojolicious::Plugin::ReCAPTCHAv2 inherits all methods from Mojolicious::Plugin and implements no extra ones.


Mojolicious::Plugin::ReCAPTCHAv2 makes the following helpers available:


Returns a HTML fragment with the widget code; you will probably want to put this in the stash, since it has to be inserted in your HTML form element when processing the template.


Call this helper when receiving the request from your website after the user submitted the form. Sends your secret, the response token from the request your received and the users IP to the reCAPTCHA server to verify the token.

You should call this only once per incoming request.

It will return either a true or false value:

false (0)

The reCAPTCHA service could not verify that the Captcha was solved by a human; either because it was a bot or because of some processing error. You should check for processing errors via recaptcha_get_errors. You should not continue with processing your users request but probably re-display the form with an added error message.

true (1)

The data is valid and the reCAPTCHA service believes that the challenge was solved by a human. You may proceed with processing the incoming request.


This helper returns a reference to an array which may contain zero, one or more error codes. The array is reset on every call to recaptcha_verify. The array can contain these official API error codes:


The secret parameter is missing.

This should not happen, since registering the plugin requires a secret configuration param which is then automatically included in the verification request.


The secret parameter is invalid or malformed.

Please check your registration data and configuration!


The response parameter is missing.

Please check if the HTML code for the widget was included at the correct position in your template. Please check the request parameters that were transferred to your server after the user submitted your form.


The response parameter is invalid or malformed.

Somebody tinkered with the request data somewhere.

Additionally the following error codes may be encountered which are defined internally by this module. Note: these codes start with "x-" to distinguish them from official error codes.


Something went wrong while trying to talk to the reCAPTCHA server.


The http request was completed successfully but Mojo::JSON could not decode the response received from the reCAPTCHA server.




Heiko Jansen <>


This software is Copyright (c) 2016 by Heiko Jansen <>.

This is free software, licensed under:

  The GNU General Public License, Version 3, June 2007