µTask is an automation engine built for the cloud. It is:

simple to operate: only a postgres DB is required
secure: all data is encrypted, only visible to authorized users
extensible: you can develop custom actions in golang

µTask allows you to model business processes in a declarative yaml format. Describe a set of inputs and a graph of actions and their inter-dependencies: µTask will asynchronously handle the execution of each action, working its way around transient errors and keeping a trace of all intermediary states until completion.

Celery is an asynchronous task queue/job queue based on distributed message passing. It is focused on real-time operation, but supports scheduling as well.

Kraken is the first and only multi-processed, multi-threaded, fault-tolerant framework for PHP. It has been written to provide easy and reliable API for creating distributed applications using PHP.

Amp is a non-blocking concurrency framework for PHP providing primitives to manage concurrency such as an event loop, promises, and asynchronous iterators.

It implements coroutines using PHP's generators to avoid callback or then() hells. Promise consumption works without callbacks and allows ordinary catch clauses just as synchronous code for handling errors.

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

React 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.

A lightweight library that provides tools for organizing asynchronous code