reCAPTCHA PHP client library

reCAPTCHA is a free CAPTCHA service that protects websites from spam and abuse. This is a PHP library that wraps up the server-side verification step required to process responses from the reCAPTCHA service. This client supports both v2 and v3.

• reCAPTCHA: https://cloud.google.com/security/products/recaptcha
• This repo: https://github.com/google/recaptcha
• Hosted demo: https://recaptcha-demo.appspot.com/
• Version: 1.4.2
• License: BSD, see LICENSE

[!IMPORTANT] reCAPTCHA Enterprise is supported via the Google Cloud Recaptcha Enterprise for PHP client.

Installation

Composer (recommended)

Use Composer to install this library from Packagist: google/recaptcha

Run the following command from your project directory to add the dependency:

composer require google/recaptcha "^1.4"

Alternatively, add the dependency directly to your composer.json file:

"require": {
    "google/recaptcha": "^1.4"
}

Support for earlier versions of PHP

From the 1.3 release support moved to PHP 8 and up. For earlier versions, you will need to stay with the 1.2 releases.

Direct download

Download the ZIP file and extract into your project. An autoloader script is provided in src/autoload.php which you can require into your script. For example:

require_once '/path/to/recaptcha/src/autoload.php';
$recaptcha = new \ReCaptcha\ReCaptcha($secret);

The classes in the project are structured according to the PSR-4 standard, so you can also use your own autoloader or require the needed files directly in your code.

Usage

First obtain the appropriate keys for the type of reCAPTCHA you wish to integrate at https://www.google.com/recaptcha/admin.

Then follow the integration guide on the developer site to add the reCAPTCHA functionality into your frontend.

This library comes in when you need to verify the user’s response. On the PHP side you need the response from the reCAPTCHA service and secret key from your credentials. Instantiate the ReCaptcha class with your secret key, specify any additional validation rules, and then call verify() with the reCAPTCHA response (usually in $_POST[\ReCaptcha\ReCaptcha::USER_TOKEN_PARAMETER] or the response from grecaptcha.execute() in JS which is in $gRecaptchaResponse in the example) and user’s IP address. For example:

<?php
$recaptcha = new \ReCaptcha\ReCaptcha($secret);
$resp = $recaptcha->setExpectedHostname('recaptcha-demo.appspot.com')
                  ->verify($gRecaptchaResponse, $remoteIp);
if ($resp->isSuccess()) {
    // Verified!
} else {
    $errors = $resp->getErrorCodes();
}

The following methods are available:

• setExpectedHostname($hostname): ensures the hostname matches. You must do this if you have disabled “Domain/Package Name Validation” for your credentials. Note: if you need to validate against multiple hostnames, do not use this method. Instead, check the $resp->getHostname() against your list of allowed hostnames after calling verify().
• setExpectedApkPackageName($apkPackageName): if you’re verifying a response from an Android app. Again, you must do this if you have disabled “Domain/Package Name Validation” for your credentials.
• setExpectedAction($action): ensures the action matches for the v3 API.
• setScoreThreshold($threshold): set a score threshold for responses from the v3 API
• setChallengeTimeout($timeoutSeconds): set a timeout between the user passing the reCAPTCHA and your server processing it.

Each of the set*() methods return the ReCaptcha instance so you can chain them together. For example:

<?php
$recaptcha = new \ReCaptcha\ReCaptcha($secret);
$resp = $recaptcha->setExpectedHostname('recaptcha-demo.appspot.com')
                  ->setExpectedAction('homepage')
                  ->setScoreThreshold(0.5)
                  ->verify($gRecaptchaResponse, $remoteIp);

if ($resp->isSuccess()) {
    // Verified!
} else {
    $errors = $resp->getErrorCodes();
}

You can find the constants for the libraries error codes in the ReCaptcha class constants, e.g. ReCaptcha::E_HOSTNAME_MISMATCH

Alternate request methods

[!NOTE] As of version 1.4.2, the default behavior has changed.

By default, the library will attempt to use cURL to make the POST request to the reCAPTCHA service. This is handled by the RequestMethod\CurlPost class. If cURL is not available, it will fall back to using stream_context_create() and file_get_contents() via the RequestMethod\Post class.

To keep the previous behavior of always using file_get_contents() regardless of cURL’s availability, you can explicitly configure it:

<?php
$recaptcha = new \ReCaptcha\ReCaptcha($secret, new \ReCaptcha\RequestMethod\Post());

You may need to use other methods for making requests in your environment. The ReCaptcha class allows an optional RequestMethod instance to configure this. For example, if you want to force the use of cURL you can do this:

<?php
$recaptcha = new \ReCaptcha\ReCaptcha($secret, new \ReCaptcha\RequestMethod\CurlPost());

Alternatively, you can also use a socket:

<?php
$recaptcha = new \ReCaptcha\ReCaptcha($secret, new \ReCaptcha\RequestMethod\SocketPost());

For more details on usage and structure, see ARCHITECTURE.

Examples

You can see examples of each reCAPTCHA type in examples/. You can run the examples locally by using the Composer script:

composer run-script serve-examples

This makes use of the in-built PHP dev server to host the examples at http://localhost:8080/

These are also hosted on Google AppEngine Flexible environment at https://recaptcha-demo.appspot.com/. This is configured by app.yaml which you can also use to deploy to your own AppEngine project.

Contributing

No one ever has enough engineers, so we’re very happy to accept contributions via Pull Requests. For details, see CONTRIBUTING

To set up your local checkout, install the dependencies:

composer install

If you add new dependencies to the project, make sure you commit the lock file:

composer update
git add composer.json composer.lock

Before committing code, make sure it meets the quality and formatting standards:

composer run phpstan
composer run lint-fix

Run the tests before submitting. Make sure you add or update tests to cover any changes you make:

composer run test