The Akismet API is open and alternative uses of it are encouraged. We have documented the methods it uses here, and we'll be expanding the API docs based on feedback from the community. The WordPress plugin is GPL and fine for use as a reference.
People have already begun implementing Akismet for other systems and platforms, here's the ones we know about:
We've heard requests for Akismet to be integrated with Mediawiki, phpBB, contact forms, and guestbooks. If any of these sounds exciting to you and you hack it, we'll be happy to promote your project here.
We love developers. Lurve! If you want to develop the Akismet plugin or on top of the Akismet API, the best first step is to join the Spam Stoppers mailing list where all the magic happens.
If you want to get in touch with the Akismet team in a more personal fashion, go ahead and use the contact form.
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