Monthly Downloads: 8,365
Programming language: Elixir
License: MIT License
Latest version: v3.0.0

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Build Status Coverage Status Hex.pm

A simple Elixir package for implementing reCAPTCHA in Elixir applications.

Migration from 1.x

Breaking Changes

  1. Template functionality is now in a separate module: Recaptcha.Template. Please note: in future templating may move to a Phoenix specific package.
  2. verify API has changed, see the code for documentation of the new API.

Most other questions about 2.x should be answered by looking over the documentation and the code. Please raise an issue if you have any problems with migrating.


  1. Add recaptcha to your mix.exs dependencies
  defp deps do
      {:recaptcha, "~> 3.0"},
  1. List :recaptcha as an application dependency
  def application do
    [ extra_applications: [:recaptcha] ]
  1. Run mix do deps.get, compile


By default the public and private keys are loaded via the RECAPTCHA_PUBLIC_KEY and RECAPTCHA_PRIVATE_KEY environment variables.

  config :recaptcha,
    public_key: {:system, "RECAPTCHA_PUBLIC_KEY"},
    secret: {:system, "RECAPTCHA_PRIVATE_KEY"}

JSON Decoding

By default reCaptcha will use Jason to decode JSON responses, this can be changed as such:

  config :recaptcha, :json_library, Poison


Render the Widget

Use raw (if you're using Phoenix.HTML) and Recaptcha.Template.display/1 methods to render the captcha widget.

For recaptcha with checkbox

<form name="someform" method="post" action="/somewhere">
  <%= raw Recaptcha.Template.display %>

For invisible recaptcha

<form name="someform" method="post" action="/somewhere">
  <%= raw Recaptcha.Template.display(size: "invisible") %>

To change the position of the invisible recaptcha, use an option badge. See https://developers.google.com/recaptcha/docs/invisible on the date-badge.

Since recaptcha loads Javascript code asynchronously, you cannot immediately submit the captcha form. If you have logic that needs to know if the captcha code has already been loaded (for example disabling submit button until fully loaded), it is possible to pass in a JS-callback that will be called once the captcha has finished loading. This can be done as follows:

<form name="someform" method="post" action="/somewhere">
  <%= raw Recaptcha.Template.display(onload: "myOnLoadCallback") %>

And then in your JS code:

function myOnLoadCallback() {
  // perform extra actions here

display method accepts additional options as a keyword list, the options are:

Option Action Default
noscript Renders default noscript code provided by google false
public_key Sets key to the data-sitekey reCaptcha div attribute Public key from the config file
hl Sets the language of the reCaptcha en

Verify API

Recaptcha provides the verify/2 method. Below is an example using a Phoenix controller action:

  def create(conn, params) do
    case Recaptcha.verify(params["g-recaptcha-response"]) do
      {:ok, response} -> do_something
      {:error, errors} -> handle_error

verify method sends a POST request to the reCAPTCHA API and returns 2 possible values:

{:ok, %Recaptcha.Response{challenge_ts: timestamp, hostname: host}} -> The captcha is valid, see the documentation for more details.

{:error, errors} -> errors contains atomised versions of the errors returned by the API, See the error documentation for more details. Errors caused by timeouts in HTTPoison or Jason encoding are also returned as atoms. If the recaptcha request succeeds but the challenge is failed, a :challenge_failed error is returned.

verify method also accepts a keyword list as the third parameter with the following options:

Option Action Default
timeout Time to wait before timeout 5000 (ms)
secret Private key to send as a parameter of the API request Private key from the config file
remote_ip Optional. The user's IP address, used by reCaptcha no default


In order to test your endpoints you should set the secret key to the following value in order to receive a positive result from all queries to the Recaptcha engine.

config :recaptcha,
  secret: "6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe"

Setting up tests without network access can be done also. When configured as such a positive or negative result can be generated locally.

config :recaptcha,
  http_client: Recaptcha.Http.MockClient,
  secret: "6LeIxAcTAAAAAGG-vFI1TnRWxMZNFuojJ4WifJWe"

  {:ok, _details} = Recaptcha.verify("valid_response")

  {:error, _details} = Recaptcha.verify("invalid_response")


Check out CONTRIBUTING.md if you want to help.


MIT License.

*Note that all licence references and agreements mentioned in the recaptcha README section above are relevant to that project's source code only.