Libxml

Libxml2 is the XML C parser and toolkit developed for the Gnome project (but usable outside of the Gnome platform), it is free software available under the MIT License. Libxml2 is known to be very portable, the library should build and work without serious troubles on a variety of systems (Linux, Unix, Windows, CygWin, MacOS, MacOS X, RISC Os, OS/2, VMS, QNX, MVS, VxWorks, ...)

Libxml2 also provides support for Document Object Model (DOM), but it doesn't implement the API itself, gdome2 does this on top of libxml2. RFC 959 : libxml2 implements a basic FTP client code, RFC 1945 : HTTP/1.0, again a basic HTTP client code, SAX: a SAX2 like interface and a minimal SAX1 implementation compatible with early expat versions.