Programming language: Scala
Latest version: v3.0.0

Monix alternatives and similar packages

Based on the "Functional Reactive Programming" category

  • Vert.x

    Vert.x is a tool-kit for building reactive applications on the JVM
  • RxScala

    Reactive Extensions for Scala
  • Scala.Rx

    An experimental library for Functional Reactive Programming in Scala (reactive variables). Scala.js compatible.
  • typed-actors

    compile-time typechecked akka actors
  • SynapseGrid

    an FRP framework for constructing reactive real-time immutable data flow systems. It implements an original way of running and organizing event-driven systems based on Petri nets. The topology can be viewed as a .dot graph. The library is compatible with Akka and can seamlessly communicate with other actors.
  • REScala

    REScala is a library for functional reactive programming on the JVM and the Web. It provides a rich API for event stream transformations and signal composition with managed consistent up-to-date state and minimal syntactic overhead.
  • Reactive Collections

    A library that incorporates event streams and signals with specialized collections called reactive containers, and expresses concurrency using isolates and channels.
  • scala.frp

    Functional Reactive Programming for Scala (event streams).

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Asynchronous, Reactive Programming for Scala and Scala.js.

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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 cleanly interact 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, being one of the parents and implementors of cats-effect.

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


  • exposes the kick-ass Observable, Iterant, Task and Coeval data types, along with all the support they need
  • modular, only use what you need
  • designed for true asynchronicity, running on both the JVM and Scala.js
  • really good test coverage, code quality and API documentation as a primary project policy


See monix-sample for a project exemplifying Monix used both on the server and on the client.


The packages are published on Maven Central.

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

libraryDependencies += "io.monix" %% "monix" % "3.0.0"


Monix 3.x is modular by design, so you can pick and choose:

  • 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-execution exposes the low-level execution environment, or more precisely Scheduler, Cancelable, Atomic, Local, CancelableFuture and Future based abstractions from monix-catnap.
  • 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

Versioning Scheme

The versioning scheme follows the Semantic Versioning (semver) specification, meaning that stable versions have the form $major.$minor.$patch, such that:

  1. $major version updates make binary incompatible API changes
  2. $minor version updates adds functionality in a backwards-compatible manner, and
  3. $patch version updates makes backwards-compatible bug fixes

For development snapshots may be published to Sonatype at any time. Development versions have the form: $major.$minor.$patch-$hash (example 3.0.0-d3288bb).

The $hash is the 7 character git hash prefix of the commit from which the snapshot was published. Thus, "snapshots" can be used as repeatable upstream dependencies if you're feeling courageous. NO GUARANTEE is made for upgrades of development versions, use these at your own risk.



API Documentation:

(contributions are welcome)



The Monix project welcomes contributions from anybody wishing to participate. All code or documentation that is provided must be licensed with the same license that Monix is licensed with (Apache 2.0, see LICENSE.txt).

People are expected to follow the [Scala Code of Conduct](./CODE_OF_CONDUCT.md) 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](CONTRIBUTING.md).

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


All code in this repository is licensed under the Apache License, Version 2.0. See [LICENCE.txt](./LICENSE.txt).


YourKit supports the Monix project with its full-featured Java Profiler. YourKit, LLC is the creator YourKit Java Profiler and YourKit .NET Profiler, innovative and intelligent tools for profiling Java and .NET applications.

Development of Monix has been initiated by Eloquentix engineers, with Monix being introduced at E.ON Connecting Energies, powering the next generation energy grid solutions.


Here's a (non-exhaustive) list of companies that use Monix in production. Don't see yours? You can add it in a PR!

*Note that all licence references and agreements mentioned in the Monix README section above are relevant to that project's source code only.