Reduce Blog Comment SPAM – SI Captcha Plugin

One of the latest WordPress plugins that I have been testing is the SI Captcha Plugin created by Mike Challis.  It has some excellent features and can be a very useful plugin to help combat blog comment SPAM. Although most bloggers using WordPress will install Akismet it is not able to do the best job and this is why I have now installed this captcha plugin as well.

With over 624,400 times downloaded, 178 ratings and a star rating of 4 and a half out of 5 on the WordPress download page I highly recommend giving SI Captcha Anti-Spam plugin a chance. The details of the current version features are displayed below as well as more details on how you can get a copy for your self.

Features of SI Captcha:

  • Configure from Admin panel
  • Valid HTML
  • Section 508 and WAI Accessibility Validation.
  • 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.
  • I18n language translation support

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


  • Works with WordPress 2.8+, WPMU, and BuddyPress 1.1 -> 1.2.3 (WordPress 3.0+ is highly recommended)
  • PHP 4.3 or above with GD2 library support. (PHP5 is highly recommended)
  • (WP 2 series) 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.

Here is the WordPress download page of SI Captcha:

Daniel Hall

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3 Responses to “Reduce Blog Comment SPAM – SI Captcha Plugin”

  1. Pinocchio says:

    I have also tried SI Captcha.
    It passes tons of spam.
    It is easily passable by spam bots

  2. Daniel Hall says:

    Hi Pinocchi,

    Yes, as I have been testing it and I have not seen any great improvements. What do you recommend that you would like to share with our readers?

  3. Pinocchio says:

    My (previous) reply with 2 URLs in body of comment + link to my blog in Website field just disappeared silently.

    If you use Akismet plz restore that comment from spam since I know from my previous commenting that only filling Website field with URL to my blog without any URLs in comment is usually enough for AKISMET to mark my comment as spam.
    And frequently my comments even without any URLs are not appearing at all

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