Skip to content
Go to file

Reactor Project

Join the chat at


Starting from 3.0, Reactor is now organized into multiple projects:

Reactor Project

A set of compatible versions for all these projects is curated under a BOM ("Bill of Materials").

Using the BOM with Maven

In Maven, you need to import the bom first:


Notice we use the <dependencyManagement> section and the import scope.

Next, add your dependencies to the relevant reactor projects as usual, except without a <version>:


Using the BOM with Gradle

Gradle 5.0+

Use the platform keyword to import the Maven BOM within the dependencies block, then add dependencies to your project without a version number.

dependencies {
     // import BOM
     implementation platform('io.projectreactor:reactor-bom:2020.0.0-M2')

     // add dependencies without a version number
     implementation 'io.projectreactor:reactor-core'

Gradle 4.x and earlier

Gradle versions prior to 5.0 have no core support for Maven BOMs, but you can use Spring's gradle-dependency-management plugin.

First, apply the plugin from Gradle Plugin Portal (check and change the version if a new one has been released):

plugins {
    id "io.spring.dependency-management" version "1.0.6.RELEASE"

Then use it to import the BOM:

dependencyManagement {
     imports {
          mavenBom "io.projectreactor:reactor-bom:2020.0.0-M2"

Then add a dependency to your project without a version number:

dependencies {
     compile 'io.projectreactor:reactor-core'

BOM Versioning Scheme

The BOM can be imported in Maven, which will provide a set of default artifact versions to use whenever the corresponding dependency is added to a pom without an explicitly provided version.

As the different artifacts versions are not necessarily aligned, the BOM represents a release train with an heterogeneous range of versions that are curated to work together. The artifact version follows the YYYY.MINOR.MICRO-QUALIFIER scheme since Europium, where:

  • YYYY is the year of the first GA release in a given release cycle (like 3.4.0 for 3.4.x)
  • .MINOR is a 0-based number incrementing with each new release cycle ** in the case of the BOM it allows discerning between release cycles in case two get first released the same year
  • .PATCH is a 0-based number incrementing with each service release
  • -QUALIFIER is a textual qualifier, which is omitted in the case of GA releases (see below)

On top of the artifact version, each release train has an associated codename, a chemical name from the Periodic Table of Elements in growing alphabetical order, for reference in discussions.

So far, the release trains code names are:

  • Aluminium for the 3.0.x generation of Reactor-Core (💡)
  • Bismuth for the 3.1.x generation (💡)
  • Californium for the 3.2.x generation (💡)
  • Dysprosium for the 3.3.x generation (💡)
  • Europium (2020.0) for the 3.4.x generation (💡)

NOTE: Up until Dysprosium, the BOM was versioned using a release train scheme with a codename followed by a qualifier, and the qualifiers were slightly different. For example: Aluminium-RELEASE (first GA release, would now be something like YYYY.0.0), Bismuth-M1, Californium-SR1 (service release would now be something like YYYY.0.1), Dysprosium-RC1, Dysprosium-BUILD-SNAPSHOT (after each patch, we'd go back to the same snapshot version. would now be something like YYYY.0.X-SNAPSHOT so we get 1 snapshot per PATCH).


Join the initiative, fork, discuss and PR anytime. Roadmap is collaborative and we do enjoy new ideas, simplifications, doc, feedback, and, did we mention feedback already ;) ? As any other open source project, you are the hero, Reactor is only useful because of you and we can't wait to see your pull request mate !

GitHub forks license


Community / Support

  • Join the chat at
  • GitHub issues
  • Twitter URL

Detail of Projects

Reactor Core

Reactor Core

Reactive foundations for apps and frameworks and reactive extensions inspired API with Mono (1 element) and Flux (n elements) types

Reactor Netty

Reactor Netty

TCP and HTTP client and server.

Reactor Addons

Reactor Addons

Extra projects adding features to reactor:

  • reactor-adapter: adapt to/from various libraries, mainly RxJava 2.
  • reactor-extra: Retry utils, Math utils, ...
  • reactor-logback: logback adapter for Flux/Mono log() feature.

Snapshot Artifacts

While Stable Releases are synchronized with Maven Central, fresh snapshot and milestone artifacts are provided in the repositories.

To add this repo to your Maven build, add it to the <repositories> section like the following:

	    <name>Spring Snapshot Repository</name>

To add it to your Gradle build, use the repositories configuration like this:

repositories {
	maven { url '' }

You should then be able to import a -SNAPSHOT version of the BOM, like 2020.0.1-SNAPSHOT for the snapshot of the second service release of 2020.0 (Europium).

Reactive Streams Commons

In a continuous mission to design the most efficient concurrency operators for Reactive Streams, a common effort -codename Reactive Streams Commons- has begun. Reactor is fully aligned with RSC design and is directly inlining RSC within its stable API contract scoped under reactor-core. Reactive Streams Commons is a research effort shared with everyone and is demanding of efficient stream processing challengers, therefore it is naturally decoupled of any framework noise.

Sponsored by Pivotal


Reactor Bill Of Materials (tracking reactor-core, reactor-netty and more)



You can’t perform that action at this time.