Cross-platform asynchronous I/O. [BSD]

Cross-platform event loop library. [BSD]

An Open Source Implementation of the Actor Model in C++. [BSD-3-Clause] website

C++ wrapper for libuv. [MIT]

A cross-platform C++ library for network and low-level I/O programming. [Boost] website

a simple interface, high-performance network library based on C++11. [MIT]

Header only library that implements Promise/A+ standard. [Anti-996]

An event queue which focuses on thread safety and provides dependency injection. [MIT]

A full-featured and high-performance event loop that is loosely modelled after libevent, but without its limitations and bugs. [BSD and GPL]

An event notification library. [BSD]