Tokio is described as '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 blazing fast, lightweight and reliable' and is an app in the Development category. There are three alternatives to Tokio for Linux, Mac, Windows and C++. The best alternative is libuv, which is both free and Open Source. Other great apps like Tokio are libevent (Free, Open Source) and libev (Free, Open Source).
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.