Home page: http://s11n.net/
License: Public Domain
Some source code falls under other licenses such as LGPL or BSD, as described in their source files. To the best of my understanding, s11n falls into Section 5 of the LGPL, and need not be released under that license. (More specifically, it contains no LGPL code, but uses features provided by a couple of LGPL'd classes.)
Please see the library manual for information about using the library, the list of features and requirements, etc.
This library contains a lot of classes, but only a handful of them are significant for 99% of client code:
The library manual contains information which must be understood before using this library, or you're likely to end up in Compile-error Hell very quickly.