The libc wrapper project aims to help client/server software development teams willing to gain full functional test coverage. It makes it possible to run several instances of the full software stack on the same machine and perform locally functional testing of complex network configurations. Daemons run with privilege separation and required user and group accounts, irrespective to the hosting system. The libc wrapper project does not require virtualization and can be used to build environments with different operating systems. The project consists of a socket wrapper, NSS module wrapper (users, groups, hosts), and a (s)uid wrapper with support for GNU/Linux, BSD, OSX, and Solaris.