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ReCaptcha helpers for ruby apps
Ruby HTML CSS JavaScript
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demo bundle Mar 20, 2016
lib v3.0.0 May 27, 2016
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.gitignore Adding recaptcha token module. Using it. Nov 18, 2015
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Rakefile bump Nov 18, 2015
recaptcha.gemspec noskip Nov 20, 2015


Author: Jason L Perry (
Copyright: Copyright (c) 2007-2013 Jason L Perry
License: MIT

This plugin adds helpers for the reCAPTCHA API. In your views you can use the recaptcha_tags method to embed the needed javascript, and you can validate in your controllers with verify_recaptcha or verify_recaptcha!, which throws an error on failiure.

Rails Installation

obtain a reCAPTCHA API key.

gem "recaptcha", require: "recaptcha/rails"

Keep keys out of the code base with environment variables.
Set in production and locally use dotenv, make sure to add it above recaptcha.

Otherwise see Alternative API key setup.

export RECAPTCHA_PUBLIC_KEY  = '6Lc6BAAAAAAAAChqRbQZcn_yyyyyyyyyyyyyyyyy'
export RECAPTCHA_PRIVATE_KEY = '6Lc6BAAAAAAAAKN3DRm6VA_xxxxxxxxxxxxxxxxx'

Add recaptcha_tags to the forms you want to protect.

<%= form_for @foo do |f| %>
  # ... other tags
  <%= recaptcha_tags %>
  # ... other tags
<% end %>

And, add verify_recaptcha logic to each form action that you've protected.

# app/controllers/users_controller.rb
@user =[:user].permit(:name))
if verify_recaptcha(model: @user) &&
  redirect_to @user
  render 'new'

Sinatra / Rack / Ruby installation

See sinatra demo for details.

  • add gem 'recaptcha' to Gemfile
  • set env variables
  • include Recaptcha::ClientHelper where you need recaptcha_tags
  • include Recaptcha::Verify where you need verify_recaptcha


Some of the options available:

Option Description
:noscript Include content (default true)
:display Takes a hash containing the theme and tabindex options per the API. (default nil), options: 'red', 'white', 'blackglass', 'clean', 'custom'
:ajax Render the dynamic AJAX captcha per the API. (default false)
:public_key Override public API key
:error Override the error code returned from the reCAPTCHA API (default nil)
:size Specify a size (default nil)
:hl Optional. Forces the widget to render in a specific language. Auto-detects the user's language if unspecified. (See language codes)

You can also override the html attributes for the sizes of the generated textarea and iframe elements, if CSS isn't your thing. Inspect the source of recaptcha_tags to see these options.


This method returns true or false after processing the parameters from the reCAPTCHA widget. Why isn't this a model validation? Because that violates MVC. You can use it like this, or how ever you like. Passing in the ActiveRecord object is optional, if you do--and the captcha fails to verify--an error will be added to the object for you to use.

Some of the options available:

Option Description
:model Model to set errors.
:attribute Model attribute to receive errors. (default :base)
:message Custom error message.
:private_key Override private API key.
:timeout The number of seconds to wait for reCAPTCHA servers before give up. (default 3)
:response Custom response parameter. (default: params['g-recaptcha-response'])
:hostname Expected hostname or a callable that validates the hostname, see domain validation and hostname docs. (default: nil, but can be changed by setting config.hostname)

I18n support

reCAPTCHA passes two types of error explanation to a linked model. It will use the I18n gem to translate the default error message if I18n is available. To customize the messages to your locale, add these keys to your I18n backend:

recaptcha.errors.verification_failed error message displayed if the captcha words didn't match recaptcha.errors.recaptcha_unreachable displayed if a timeout error occured while attempting to verify the captcha

Also you can translate API response errors to human friendly by adding translations to the locale (config/locales/en.yml):

      incorrect-captcha-sol: 'Fail'


By default, reCAPTCHA is skipped in "test" and "cucumber" env. To enable it during test:


Alternative API key setup


# config/initializers/recaptcha.rb
Recaptcha.configure do |config|
  config.public_key  = '6Lc6BAAAAAAAAChqRbQZcn_yyyyyyyyyyyyyyyyy'
  config.private_key = '6Lc6BAAAAAAAAKN3DRm6VA_xxxxxxxxxxxxxxxxx'
  # Uncomment the following line if you are using a proxy server:
  # config.proxy = ''


For temporary overwrites (not thread safe).

Recaptcha.with_configuration(public_key: '12345') do
  # Do stuff with the overwritten public_key.

Per call

Pass in keys as options at runtime, for code base with multiple reCAPTCHA setups:

recaptcha_tags public_key: '6Lc6BAAAAAAAAChqRbQZcn_yyyyyyyyyyyyyyyyy'


verify_recaptcha private_key: '6Lc6BAAAAAAAAKN3DRm6VA_xxxxxxxxxxxxxxxxx'


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