Blogging infrastructure company Six Apart is launching a new free open source product this morning into beta called TypePad AntiSpam. While the product is new, the technology behind it has been used by Six Apart since May 2007 on millions of hosted TypePad blogs. Now they are offering it as a web service for other blogging platforms, too.

TypePad AntiSpam is clearly aimed at Akismet, a similar spam fighting tool offered by arch-rival Automattic. Like Akismet, TypePad AntiSpam takes a multi-headed heuristic approach to detecting and blocking comment spam on blogs. But TypePad’s product is free – Akismet charges $5/month for commercial blogs making more than $500/month in revenue, and has performance limitations on the free version.

TypePad AntiSpam is also open source, and anyone can download the source code and create their own spam tool based on it. Akismet isn’t open source, although they have an API that allows developers to, among other things, develop additional integration tools for blogging platforms.

We are long time users of Akismet on the TechCrunch blogs, and I’ve included it in my last two yearly lists of products I can’t live without (2007, 2008) along with Wordpress, Automattic’s blogging software. Akismet blocks over 15,000 spam comments per day on TechCrunch.

But last week we switched to TypePad AntiSpam as a test, crossed our fingers and hoped for the best. After a week I’m pleased to say that as good as Akismet is, the TypePad product has performed as good or better for us.

The product classifies comments as “ham” (good), “spam” (bad) or unknown (moderation). So far I’ve seen no good comments hit the spam folder (false positives), something that happens regularly with Akismet. Only a handful of spam comments made it to the site (false negatives). It seems like the rate of false negatives is lower than Akismet, but the team reviews the site for these regularly and so it’s impossible to compare them statistically, I’m just making a guestimate.

Twice now a large group of spam comments hit the moderation queue, but Six Apart says it was their system thinking we were under a denial of service attack from the sheer flow of spam attempts and triggering everything to moderation. They’ve now adjusted for that, and we haven’t seen it again.

TypePad AntiSpam is available now via plugins for Wordpress and Movable Type. Akismet has a much longer list of supported platforms – Six Apart says they will add more over time and, like Akismet, will rely on the developer community to pitch in as well.

If you are a blogger and don’t use a service to manage spam, you’ll want to use Akismet or TypePad AntiSpam. I recommend either. For now, we’ll stick with TypePad, and continue to report on how its doing.

Mollom is a new blog spam prevention tool that’s shaping up to be serious competition to Automattic’s Akismet, the current market leader.

Belgium based Mollom was founded earlier this year by Dries Buytaert, the founder and project lead of the Drupal project and Benjamin Schrauwen, a Post-Doc researcher at Ghent University and Machine Learning expert. Mollom automatically blocks comment form spam, contact form spam and fake user accounts using a filtering technique based on the combination of content analysis and CAPTCHA challenges.

When new content is analyzed by Mollom’s intelligent text-analysis filter, and Mollom is unsure whether it is ham or spam, it asks the user to answer a CAPTCHA challenge. This challenge-response procedure doesn’t block human users. If an unwanted message still makes it onto a website, users can help fight back by reporting to Mollom. The service learns from its mistakes.

According to statistics from Mollom (they publish a full scorecard here), the service is 99.94% accurate, making 6 mistakes per 10,000 comments, but one key to the service is its ability to learn as it goes along, so the team is aiming to improve those figures over time.

The business model will be similar to Akismet (they’re currently in beta testing only); the basic Mollom service will be free with commercial/ high-traffic websites paying but getting more advanced features, improved reliability and performance. They also plans to offer dedicated, managed Mollom servers for high-end users. Current Mollom users include Sony BMG, Adobe and FastCompany.

Buytaert told me that although offering the same features as the competition, Mollom’s goal goes further than spam-blocking alone.

We want to increase the overall quality of your site’s content. For example, Mollom’s CAPTCHA service already helps block fake user accounts, and we are experimenting with various automated content-quality assessments, including blocking obscene, violent and profane content.

The service is already getting a lot of positive buzz in the Drupal community and the statistics are impressive. They don’t currently have a WordPress version, but they did ask that I mention they’re looking for a WordPress developer to write one, contact details here if you’re interested.

On January 4 we reported that the Akismet filter had stopped a million spam comments from reaching TechCrunch. At that point we’d been using it for about nine months.

The number of blocked spam comments is now two million, just ten weeks later. That works out to about 15,000 spam comments hitting TechCrunch every day.

If we did not have Akismet, we couldn’t allow anonymous commenting here on TechCrunch. We used to go through all spam comments to pick out the occasional false positive and accept it. Now, there are just too many to go through. All comments marked by Akismet as spam get deleted almost immediately.

We’ve now implemented a Wordpress-recommended custom plugin that turns comments off on posts that are more than two weeks old. This will significantly reduce the overall amount of spam that hits the blog, so I don’t expect to see this total spam number continue to increase exponentially.

I named blog spam catcher Akismet as one of the products I couldn’t live without in a post a few days ago. Today we hit the magic number – Akismet has captured over 1 million spam comments and trackbacks, just on TechCrunch. That’s over 1 million pieces of bogus content that we didn’t have to read, sort through manually and delete.

Akismet is a relatively easy plugin to install if you use Wordpress, and there are developer tools available if you want to use it on another blogging platform or website. If you have a blog, and don’t know about Akismet, take a minute and check it out.