The Wireless Universal Resource FiLe (WURFL) is the da-facto standard Open-Source DDR (Device Description Repository, albeit WURFL's birth pre-dates the birth of the term DDR).

If you need to build a mobile application, chances are that you need to figure out what certain devices can or cannot do in real time. This is not a simple nut to crack. After all, who can tell you what old and new devices can do? And even if someone did, how can you take advantage of that information in real-time when users access your service? WURFL will solve both problems by providing you with:

• A repository of device description containing 7000+ devices (actually a lot more, if you consider firmware variations).
• An API which will let you map the HTTP request from any device to its WURFL profile (and its capabilities).

Recently, a new version of the WURFL API has been released for both Java and PHP (and shortly, the .Net version will be available as well). The new API has quite a few advantages over the old one:

• Much improved matching heursitics: with the advent of mobile browsers which disguise as Mozillates, the WURFL API also had to become smarter.
• Much reduced possibility of false positives.
• Possibility to use WURFL.xml in archived forma (.zip or .gz).
• Possibility to use multiple patch files.
• More modular: both the Java and the PHP API will allow advanced adopters to easily plug-in or replace single modules of the API.

Detailed information about the new API can be found here:
http://wurfl.sourceforge.net/newapi/

Java API (Spring-Framework based and highly configurable)
http://wurfl.sourceforge.net/njava/

PHP API (more modular, controllable, and object-oriented than the old version)
http://wurfl.sourceforge.net/nphp/