Async is a composable asynchronous I/O framework for Ruby based on io-event and timers.

"Lately I've been looking into async, as one of my projects – tus-ruby-server – would really benefit from non-blocking I/O. It's really beautifully designed." janko

Development Status



Please browse the source code index or refer to the guides below.

Getting Started

This guide gives shows how to add async to your project and run code asynchronously.

Asynchronous Tasks

This guide explains how asynchronous tasks work and how to use them.

Event Loop

This guide gives an overview of how the event loop is implemented.


Async is compatible with a wide range of different Ruby versions.


We welcome contributions to this project.

  1. Fork it.
  2. Create your feature branch (git checkout -b my-new-feature).
  3. Commit your changes (git commit -am 'Add some feature').
  4. Push to the branch (git push origin my-new-feature).
  5. Create new Pull Request.

See Also

Projects Using Async