Last week, we at Facebook celebrated the one-year anniversary of our f8 conference, where Facebook Platform was launched. It’s been quite a year, with over 24,000 applications built on the platform and over 400,000 developers building new social experiences. We see about 140 applications added to our directory per day, and nearly all of our users have added at least one application. It’s been humbling for us, and incredibly exciting.

On the anniversary of our platform launch, we want to give back to the developer community. As Facebook Platform continues to mature, we’ve been hearing from a lot of you that you’d like more tools and better information on how Facebook Platform actually works. As a starting point, we’re open-sourcing a significant part of Facebook Platform, including most of the code that runs Facebook Platform plus implementations of many of the most-used methods and tags. This release is just a first step in providing you a look into Facebook Platform, and we hope you’ll help us iterate on and improve it. You can find more information and the Facebook Open Platform downloads on our Facebook Open Source page at http://developers.facebook.com/opensource.php.

The goal of this release is to help you as developers better understand Facebook Platform as a whole and more easily build applications, whether it’s by running your own test servers, building tools, or optimizing your applications on this technology. We’ve built in extensibility points, so you can add functionality to Facebook Open Platform like your own tags and API methods. We’re also hoping you use Facebook Open Platform in ways we’ve never thought of – just as you showed off your creativity with Facebook Platform, we hope this lets you be creative with the foundation of the platform itself.

Most of this release is licensed under the Common Public Attribution License (CPAL). The CPAL is community-friendly and reflects how software works today by recognizing web services as a major way of distributing software. It also enables you to connect your brand to ours as you make modifications and updates. The rest of the code is licensed under the Mozilla Public License (MPL).

We encourage you to make the ecosystem even stronger by sharing what you’ve built with other developers. You can check out our community forums at http://forum.developers.facebook.com/.

We’ll keep working to give you the best platform for building great user experiences, and we’re looking forward to seeing what you build with Facebook Platform in the future.

Thanks for a great year – we can’t wait for the next one!