Takayuki Miyoshi

Really Simple CAPTCHA does not work alone and is intended to work with other plugins. It is originally created for <a href="https://contactform7.com/" rel="nofollow ugc">Contact Form 7</a>, however, you can use it with your own plugin.
Note: This product is “really simple” as its name suggests, i.e., it is not strongly secure. If you need perfect security, you should try other solutions.
<h4>How does it work?</h4>
Really Simple CAPTCHA does not use PHP “Sessions” for storing states, unlike many other PHP CAPTCHA solutions, but stores them as temporary files. This allows you to embed it into WordPress without worrying about conflicts.
When you generate a CAPTCHA, Really Simple CAPTCHA creates two files for it; one is an image file of CAPTCHA, and the other is a text file which stores the correct answer to the CAPTCHA.
The two files have the same (random) prefix in their file names, for example, “a7hk3ux8p.png” and “a7hk3ux8p.txt.” In this case, for example, when the respondent answers “K5GF” as an answer to the “a7hk3ux8p.png” image, then Really Simple CAPTCHA calculates hash of “K5GF” and tests it against the hash stored in the “a7hk3ux8p.txt” file. If the two match, the answer is confirmed as correct.
<h4>How to use with your plugin</h4>
Note: Below are instructions for plugin developers.
First, create an instance of ReallySimpleCaptcha class:
<pre><code>$captcha_instance = new ReallySimpleCaptcha();
</code></pre>
You can change the instance variables as you wish.
<pre><code>// Change the background color of CAPTCHA image to black
$captcha_instance->bg = array( 0, 0, 0 );
</code></pre>
See really-simple-captcha.php if you are interested in other variables.
Generate a random word for CAPTCHA.
<pre><code>$word = $captcha_instance->generate_random_word();
</code></pre>
Generate an image file and a corresponding text file in the temporary directory.
<pre><code>$prefix = wp_rand();
$captcha_instance->generate_image( $prefix, $word );
</code></pre>
Then, show the image and get an answer from respondent.
Check the correctness of the answer.
<pre><code>$correct = $captcha_instance->check( $prefix, $the_answer_from_respondent );
</code></pre>
If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human.
And last, remove the temporary image and text files, as they are no longer in use.
<pre><code>$captcha_instance->remove( $prefix );
</code></pre>
That’s all.
If you wish to see a live sample of this, you can try <a href="https://contactform7.com/captcha/" rel="nofollow ugc">Contact Form 7</a>.

Really Simple CAPTCHA

Needed this for an installation with custom forms. I used the plugin developers instructions and was able to make a fully custom implementation based on server side validation within 30 minutes. No more spam bots misusing the forms. Thank you!

Great work - easy to implement

Really Simple CAPTCHA is a CAPTCHA module intended to be called from other plugins. It is originally created for my Contact Form 7 plugin.

ScriptsTown

Login Security Captcha is a security plugin for WordPress to add CAPTCHA or CAPTCHA-free services such as Cloudflare Turnstile and Google reCAPTCHA to the WordPress login, registration, lost password, and comment form. This is a fast and lightweight security plugin to place captcha on standard WordPress forms with minimal footprints. It can prevent spam comments and protect the login form against Brute-force attacks. It has simple settings to configure the plugin quickly.
The plugin supports Cloudflare Turnstile, Google reCAPTCHA Version 2, and Version 3 with multiple options. This is the best WordPress captcha plugin for antispam protection to secure comment form and WordPress login page. It allows you to place different versions of reCAPTCHA and also Turnstile on different forms at the same time. This plugin comes with a set of simple options to quickly set up captcha validation on the common forms.
Using this security plugin, you can change the captcha theme to light or dark depending on your preferences for Cloudflare Turnstile and Google reCAPTCHA. You can also configure various other parameters like the score value for reCAPTCHA version 3. You can monitor the error logs and have the option to disable the captcha on the comment form for logged-in users. Also, you can adjust the captcha size to compact or normal for Cloudflare Turnstile.
<h3>Login Security Captcha Features</h3>
<ul>
<li>Cloudflare Turnstile</li>
<li>Google reCAPTCHA v2</li>
<li>Google reCAPTCHA v3</li>
<li>Set reCAPTCHA v3 Position</li>
<li>Captcha Theme and Size</li>
<li>Secure Login Form</li>
<li>Secure Registration Form</li>
<li>Secure Lost Password Form</li>
<li>Protect Comment Spam</li>
<li>Monitor Error Logs</li>
<li>Prevent Brute-force Attack</li>
</ul>
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<h3>Login Security Pro Features</h3>
<ul>
<li>Limit Login Attempts by IP Address</li>
<li>Check and Monitor Last Login</li>
<li>Check Login History by Username</li>
<li>Recent Login Dashboard Widget</li>
<li>Cloudflare Turnstile Support</li>
<li>Google reCAPTCHA v2 and v3</li>
<li>Redirect after Login or Logout</li>
<li>Role-Based Redirection</li>
<li>Secure Login and Registration Form</li>
<li>Secure Lost Password Form</li>
<li>Easy to Protect Comment Spam</li>
<li>Login Form – WooCommerce</li>
<li>Lost Password Form – WooCommerce</li>
<li>Registration Form – WooCommerce</li>
<li>Secure WooCommerce Checkout Form</li>
<li>Advanced Security and Much More</li>
</ul>
Check Pro Plugin – <a href="https://scriptstown.com/wordpress-plugins/login-security-pro/" title="View Pro Features" rel="nofollow ugc">View Pro Features</a>

Login Security Captcha

Secure WordPress login, registration, and comment form with Google reCAPTCHA or Cloudflare Turnstile. Prevent Brute-force attacks and more.

Really Simple CAPTCHA vs Login Security Captcha