ptypes

PTypes(C++ Portable Types Library) is a simple alternative to the STL that includes multithreading and networking. It defines dynamic strings, variants, character sets, lists and other basic data types along with portable thread and synchronization objects, IP sockets and named pipes. Its main `target audience' is developers of complex network daemons, robots or non-visual client/server applications of any kind.

PTypes defines simple and intuitive interfaces and differs from the STL in fairly moderate use of templates. The library is portable across many modern operating systems (currently Linux, MacOS X, SunOS, FreeBSD, HP-UX and Windows). All platform-dependent issues are hidden inside. A simple web server called wshare is included in the package to demonstrate the full power of the library.

And finally, PTypes is open and free.