Akismet

Akismet, or Automattic Kismet, is a spam filtering service created by Automattic, the corporation which employs most of the main developers of the weblog platform WordPress, and released on October 25 2005. Akismet attempts to filter link spam from blog comments and spam TrackBack pings. The filter works by combining information about spam captured on all participating blogs, and then using those spam rules to block future spam. Akismet has captured one billion spam comments and pings as of March 2007.^[1]

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Many bloggers have complained of commenters being wrongfully flagged as spammers.^[2] Once a commenter is flagged as a spammer, it becomes impossible to participate on any wordpress blog.

Akismet was originally developed to integrate with a plugin for WordPress. It is now included by default in all WordPress builds since version 2.0 and activated in all WordPress.com-hosted blogs. A public Akismet API has resulted in an Automattic sponsored plugin for Movable Type,^[3] and third-party plugins for other platforms ^[4]. Released under the GNU General Public License, the Akismet plugin is free software, although the code to the Akismet system itself (and the nature of the algorithm used) has not been released.

The Akismet service is free for personal use. To use Akismet with most blogs, it is necessary to obtain a WordPress.com API key. Bloggers with a Yahoo! hosting account get a free "pro-blogger" Akismet service (which costs non-Yahoo! users $5/month) due to a deal between the two companies.^[5]

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