Captcha by BestWebSoft - Advanced Spam Protection, Math & OCR-Friendly Captcha for Site Forms

Open your WordPress admin Dashboard.
Navigate to the Captcha settings page.
Find "Enable Captcha for" and select the "Login form".
Save changes.

Any captcha answer results in an error
CAPTCHA will only display on standard registration, login, and comments forms. If using custom forms and pages, you need to modify them to display and function correctly with CAPTCHA.
Add Captcha plugin to a custom form on my WordPress website
Follow the instructions below in order to add Captcha plugin to your custom PHP or HTML form:
1. Install the Captcha plugin and activate it.
2. (Optional) If you would like to use your own settings for the custom forms you have (for example, for your contact and sign-up forms), please follow the steps below:
- Go to your theme folder, for example, 'your-wp-site/wp-content/themes/your-theme-name' where your-theme-name is the theme name you are currently using;
- Open functions.php file;
- Add the following code to the end of the file:

function add_my_forms( $forms ) {
$forms['my_contact_form'] = "Form Display Name";
return $forms;
}
add_filter( 'cptch_add_form', 'add_my_forms' );

Please don't use the next form slugs since they are predefined by plugin settings: general, wp_login, wp_register, wp_lost_password, wp_comments, bws_contact, bws_subscriber, buddypress_register, buddypress_comments, buddypress_group, cf7_contact, woocommerce_login, woocommerce_register, woocommerce_lost_password, woocommerce_checkout.
- Save file changes;
- Go to the "Settings" tab on the plugin settings page (Admin Dashboard -> Captcha); If everything is OK, you will see your form in 'Enable Captcha for' => 'External plugins' (with labels which you specified in the "cptch_add_form_tab" hook call function).
- Enable it and configure form options as you need;
- Click "Save changes";

If you don't want to use your own settings for CAPTCHA displaying in your custom form, it will use the settings from the "General" block on the plugin settings.

Open the file with the form (where you would like to add CAPTCHA);
Find a place to insert the code for the CAPTCHA output;
If you completed the instructions in point 2, then you should add:

In this example, the second parameter is a slug for your custom form.

Otherwise, insert the following lines:

<?php echo apply_filters( 'cptch_display', '' ); ?>

After that, you should add the following lines to the function of the entered data checking.
If you completed the instructions in point 2, then you should add:

In this example, the third parameter is a slug for your custom form.

Otherwise, insert the following lines:

<?php $error = apply_filters( 'cptch_verify', true );
if ( true === $error ) { /* the CAPTCHA answer is right */
/* do necessary action */
} else { /* the CAPTCHA answer is wrong or there are some other errors */
echo $error; /* display the error message or do other necessary actions in case when the CAPTCHA test was failed */
} ?>

If there is a variable in the check function responsible for the errors output, you can concatenate variable $error to this variable. If the 'cptch_verify' filter hook returns 'true', it means that you have entered the CAPTCHA answer properly. In all other cases, the function will return the string with the error message.
Why is the CAPTCHA missing in the comments form?
The plugin displays captcha for those comments forms which were written in the same way as comments forms for the standard WordPress themes. Unfortunately, the plugin is incompatible with comments forms generated by using SAAS (e.g., Disqus or JetPack comments forms). If you don't use SAAS comments forms, please follow the next steps:
1. Using FTP, please go to {wp_root_folder}/wp-content/themes/{your_theme}.
2. Find and open "comments.php" file. It is possible that the file that is used to display the comment form in your theme is called differently or comment form output functionality is inserted directly in the other templates themes (e.g., "single.php" or "page.php"). In this case, you need to open the corresponding file.
3. Make sure that the file contains one of the next hooks:

If you didn't find one of these hooks, then put the string <?php do_action( 'comment_form', $post->ID ); ?> in the comment form.
I have some problems with the plugin's work. What Information should I provide to receive proper support?
Please make sure that the problem hasn't been discussed yet on our forum (https://support.bestwebsoft.com). If no, please provide the following data along with your problem's description:
- The link to the page where the problem occurs
- The name of the plugin and its version. If you are using a pro version - your order number.
- The version of your WordPress installation
- Copy and paste into the message your system status report. Please read more here: Instruction on System Status