Event-driven, non-blocking I/O with PHP

The event loop is based on the reactor pattern (hence the name) and strongly inspired by libraries such as EventMachine (Ruby), Twisted (Python) and Node.js (V8).

ReactPHP

http://reactphp.org/

ReactPHP is a low-level library for event-driven programming in PHP. At its core is an event loop, on top of which it provides low-level utilities, such as: Streams abstraction, async dns resolver, network client/server, http client/server, interaction with processes. Third-party libraries can use these components to create async network clients/servers and more.

AMPHP