libuv is a software library that provides asynchronous event notification. libuv supports epoll(4), kqueue(2), Windows IOCP, and Solaris event ports. It is primarily designed for use in Node.js but it is also used by other software projects.
libevent is an asynchronous event notification software library. The libevent API provides a mechanism to execute a callback function when a specific event occurs on a file descriptor or after a timeout has been reached.
Tokio is an open source library providing an asynchronous, event driven platform for building fast, reliable, and lightweight network applications. It leverages Rust's ownership and concurrency model to ensure thread safety. Tokio is a blazing fast, lightweight and reliable.