libuv (Unicorn Velociraptor Library) is a multi-platform C library that provides support for asynchronous I/O based on event loops. It supports epoll(4), kqueue(2), Windows IOCP, and Solaris . It is primarily designed for use in Node.js but it is also used by other software projects. It was originally an abstraction around or Microsoft IOCP, as supports only select(2) and doesn't support poll(2) and IOCP on Windows. In node-v0.9.0's version of libuv, the dependency on libev was removed.