SI CAPTCHA Anti-Spam – WordPress Plugin by Mike Challis


Adds CAPTCHA anti-spam methods to WordPress on the comment form, registration form, login, or all. In order to post comments or regiser, users will have to type in the phrase shown on the image. This prevents spam from automated bots. Adds security. Works great with Akismet. Also is fully WPMU and BuddyPress compatible.

You can see it in use on my blog here: Long Beach WA – Weather Blog.

Some of the many features include:

  • Configure from Admin panel
  • Allows Trackbacks and Pingbacks
  • Setting to hide the CAPTCHA from logged in users and or admins
  • Setting to show the CAPTCHA on the comment form, registration form, login, or all.
  • Valid HTML
  • Section 508 and WAI Accessibility Validation.
  • JavaScript is not required
  • I18n language translation support
  • (see readme.txt inside the zip file for full instructions)

Captcha Image Support:

  • Open-source free PHP CAPTCHA library by is included.
  • Abstract background with multi colored, angled, and transparent text
  • Arched lines through text
  • Generates audible CAPTCHA files in WAV format
  • Refresh button to reload captcha if you cannot read it


  1. captcha on the comment form
  2. captcha on the registration form
  3. Captcha Options tab on the Admin Plugins page


  • Works with WordPress 2.6+, WPMU, and BuddyPress
  • PHP 4.0.6 or above with GD2 library support.
  • Your theme must have a <?php do_action(‘comment_form’, $post->ID); ?> tag inside your comments.php form. Most themes do. The best place to locate the tag is before the comment textarea, you may want to move it if it is below the comment textarea.


  1. Upload the ‘si-captcha-for-wordpress’ folder to the ‘/wp-content/plugins/’ directory in WordPress
  2. Activate the plugin through the `Plugins` menu in WordPress
  3. Updates are automatic. Click on “Upgrade Automatically” if prompted from the admin menu. If you ever have to manually upgrade, simply deactivate, uninstall, and repeat the installation steps with the new version.

SI CAPTCHA Anti-Spam – WordPress Plugin: [download it][version change log][FAQ]