I have just finished writing the first version of a PHP4-Class for the Anti-Blogspam-Service Defensio. Defensio basically works similar to Akismet while being less restrictive.
Both systems work by you sending the comments you recieve to Akismet's resp. Defensio's server and letting it evaluate its "spaminess". Both services then will tell you if this comment is spam. Additionally, Defensio also tells you its "spaminess" (as a decimal number between 0 and 1 and not just "yes" and "no") and a unique comment-"signature" for later identification.
That way, you may for example display spam-comments using different colors to tag them by their spaminess.
But for me, the major difference sits in the way both services allow you to use it: Once you've got an API-Key, you may use both services for free as a private user. You may also use Akismet for free in Non-Profit-Organizations but you have to add two silly "Wordpress" and "Akismet"-Buttons to every page on your site. Defensio doesn't want that. If your org-Blog receives less than 50,000 comments per month and generates less than $250 direct revenue per month, you may use Defensio for free. Without ads.
Again, if you want to use it in a company, you have to pay. For both services.
Using such a slightly more loose policy, Defensio quickly became my first choice of Spam-Defenders. But unfortunately, Defensio only supplies one single plugin for Wordpress so far. Since I am writing my own CMS/Blog-Software, I was in need to write my own interface. After a few hours work, I was done modifying Bret Kuhns Akismet PHP4-Class to work with Defensio instead.
So this is the initial release of this class, licensed under the LGPL-License.
Feedback, code-modifications and criticism is highly welcome!
More infos at the project page.
