It’s easy to forget about Windows. Despite claiming more than 50% of the server market, according to IDC data, it’s Linux that keeps stealing the headlines… and open-source developers’ affection.

And yet, look beneath the covers of most successful enterprise open-source projects, and many companies choose to run their open-source software on Windows. We may have a serious disconnect between open-source ideology and a more pragmatic need to “get stuff done.”

But that disconnect shouldn’t blind open-source developers to the need to support Windows.

Open source on Windows: The numbers

I started thinking seriously about this when I noticed that roughly 30% of MongoDB downloads are for Windows (compared to over 50% for Linux). While Miguel Diaz is likely right that this high percentage reflects “people download[ing] [MongoDB] at work where most workstations are still Windows” as “It’s easier to do a [proof of concept]” that way, there’s something more going on.

After all, JBoss used to see 50% of its downloads on Windows, and a big chunk of its production deployments too. MySQL? In March 2008, as then CEO (and current Eucalyptus CEO) Marten Mickos told me over email, 82% of MySQL direct downloads were for Windows. While Mickos was quick to clarify that those who used MySQL on Linux typically got it through a Linux distro, artificially deflating Linux’s numbers, he also stressed that the Windows percentage “is also high because Windows is so commonly used” with MySQL.

The same is true at Alfresco and other open-source projects and companies I’ve followed over the years, including Eclipse, which sees over 50% of its community choosing Windows, as its community director, Ian Skerrett, pointed out to me.

I’ve yet to see any data that contradicts my belief that Microsoft’s ecosystem is hungry for open source.

To that end, Microsoft for years has been reaching out to popular open-source communities to ensure tight integrations. Things got rolling in 2006 when Microsoft and SugarCRM announced a partnership, then kept rolling with a series of announcements like the one with Drupal in 2009.

Still, others, like Ted Wise, argue that open source is “fueled by passion,” but “No one has passion for Windows.”

Some do have that passion, of course. Just ask Steve Ballmer. No one sweats that much without passion. For some, that “passion” is simply “getting work done,” as Joe Brinkman posits:

In foxholes, there are apparently no atheists — and in IT departments, there are no true open-source ideologues.

The pragmatist’s guide to open source

Not everyone has an aversion to Windows. While there are open-source advocates who wouldn’t dream of shaking hands with Microsoft, a growing number of commercial open-source companies see opportunity in serving Microsoft’s large customer base.

One such company is Hortonworks, a provider of Hadoop and related services. As Shaun Connolly, Hortonwork’s vice president of Corporate Strategy, told me over Skype:

“Enterprise Hadoop targets a scale-out x86 architecture. Windows Server represents about 70% of the commodity server market, so it made a lot of sense to do the work to unlock that opportunity for customers who are deeply invested in Microsoft.

“We started working on Enterprise Hadoop with Microsoft in late 2011. Fast forward to today, and we simultaneously ship Hortonworks Data Platform (HDP) for both Linux and Windows shops. Moreover, HDP is embedded within Microsoft’s HDInsight service on Azure; which is a Hadoop-as-a-Service offering.

“So, looking at that, customers have the flexibility to deploy on Windows or Linux, on-premises or in the cloud. With a platform consistency that enables them to choose what’s right for them without giving up capabilities.”

Dries Buytaert, founder of Drupal, the popular content management system and co-founder of Acquia, informed me over Skype that he sees great opportunity in supporting the Microsoft stack:

“Out of a total 720,414 Drupal sites we crawled, 12,514 (or roughly 1.7%) run on on [Microsoft’s] IIS [web server]. That presents a large opportunity because a large part of the internet runs on the Microsoft stack, as Netcraft data shows. Given that 39% of the websites in the world run on Apache, 16% on NGinx and 33% on Microsoft, it would be good if we could get a bigger share of the 33% that runs on Microsoft and introduce more Microsoft developers to Drupal and Open Source.”

The financial opportunity may be even clearer than this.

There’s money in them thar Redmond Hills

One of the biggest challenges for any open-source company or project is monetization. How do you get people to pay for something they can get for free?

This question is more easily answered with the Microsoft crowd. After all, they’re conditioned to paying for software. In fact, at previous companies, I’ve always tuned our marketing automation system to more strongly score leads that use Microsoft (or Oracle), figuring that if they’re willing to pay for Windows, they should also be willing to pay for my software.

Couple that propensity to spend with Microsoft’s willingness to work with open-source projects, and there’s reason to believe that the open-source world should spend more time helping Windows users go open too.