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Asynchronous, Reactive Programming for Scala and Scala.js.

Project README


Asynchronous, Reactive Programming for Scala and Scala.js.

monix Scala version support

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Monix is a high-performance Scala / Scala.js library for composing asynchronous, event-based programs.

It started as a proper implementation of ReactiveX, with stronger functional programming influences and designed from the ground up for back-pressure and made to interact cleanly with Scala's standard library, compatible out-of-the-box with the Reactive Streams protocol. It then expanded to include abstractions for suspending side effects and for resource handling, and is one of the parents and implementors of Cats Effect.

A Typelevel project, Monix proudly exemplifies pure, typeful, functional programming in Scala, while being pragmatic, and making no compromise on performance.


  • exposes the kick-ass Observable, Iterant, Task, IO[E, A], and Coeval data types, along with all the support they need
  • modular, split into multiple sub-projects, only use what you need
  • designed for true asynchronicity, running on both the JVM and Scala.js
  • excellent test coverage, code quality, and API documentation as a primary project policy


Library dependency (sbt)

For the stable release (compatible with Cats, and Cats-Effect 2.x):

libraryDependencies += "io.monix" %% "monix" % "3.4.1"


Monix 3.x is modular by design. See the sub-modules graph:

Sub-modules graph

You can pick and choose:

  • monix-execution exposes the low-level execution environment, or more precisely Scheduler, Cancelable, Atomic, Local, CancelableFuture and Future based abstractions from monix-catnap.
  • monix-catnap exposes pure abstractions built on top of the Cats-Effect type classes; depends on monix-execution, Cats 1.x and Cats-Effect
  • monix-eval exposes Task, Coeval; depends on monix-execution
  • monix-reactive exposes Observable for modeling reactive, push-based streams with back-pressure; depends on monix-eval
  • monix-tail exposes Iterant streams for purely functional pull based streaming; depends on monix-eval and makes heavy use of Cats-Effect
  • monix provides all of the above



API Documentation:

(contributions are welcome)



The Monix project welcomes contributions from anybody wishing to participate. You must license all code or documentation provided with the Apache License 2.0, see LICENSE.txt.

You must follow the Scala Code of Conduct when discussing Monix on GitHub, Gitter channel, or other venues.

Feel free to open an issue if you notice a bug, have an idea for a feature, or have a question about the code. Pull requests are also gladly accepted. For more information, check out the contributor guide.

If you'd like to donate in order to help with ongoing maintenance:


Here's a (non-exhaustive) list of companies that use Monix in production. Don't see yours? Submit a PR ❤️


All code in this repository is licensed under the Apache License, Version 2.0. See LICENSE.

Open Source Agenda is not affiliated with "Monix" Project. README Source: monix/monix
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