# ReactiveX/RxJava

RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.

Repository: https://github.com/ReactiveX/RxJava
Canonical: https://ross.abutalabs.com/products/rxjava
Homepage: https://dsc.gg/rxjava
Language: Java
License: Apache-2.0
License Family: permissive
Topics: java, rxjava, flow, reactive-streams
Last push: 2026-08-24T05:34:22+00:00

## Health v2 (maintenance only)
Score: 98/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 96, longevity 100
- inputs: {"age_days": 4985, "days_push": 9, "days_rel": 28, "gap_med": 2.0, "n_releases_24m": 23}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 48204, forks 7591 (observed 2026-08-28T04:12:11.396944+00:00)

## What it is
RxJava is a JVM implementation of Reactive Extensions, a library for composing asynchronous and event-based programs using observable sequences. It extends the observer pattern with declarative operators that abstract away threading, synchronization, and concurrency concerns.

## Use cases
- compose asynchronous event streams in Java
- handle backpressure with Reactive Streams Flow
- replace callback-heavy code with declarative pipelines
- manage threading and schedulers for background work
- build reactive data pipelines on the JVM
- use virtual threads with reactive sequences

## When to choose
- you need mature, battle-tested reactive programming on the JVM
- you want rich operator composition for async/event streams
- you're building Android or server-side Java with complex async flows

## When to avoid
- your project targets very old Java versions incompatible with 4.x
- you prefer coroutine-based approaches like Kotlin coroutines
- simple async needs where CompletableFuture suffices

## Facets
- artifact type: library
- maturity: active
- function: concurrency, streaming, developer-tools
- domain: developer-tools, backend, cross-platform
- platform: jvm, cross-platform
- tags: reactive-streams, observable-sequences, async, event-driven, flow, android

## Member repositories
- ReactiveX/RxJava (main) score 98

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:12:11.396944+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T16:20:45.617848+00:00, confidence not recorded.
  - readme: https://github.com/ReactiveX/RxJava (fetched 2026-08-28T04:12:11.396944+00:00, sha 2a2350712b95)
  - homepage: https://dsc.gg/rxjava (fetched 2026-08-29T07:42:09.047664+00:00, sha 105501a07d1e)
- Data as of 2026-08-30T08:39:29.467469+00:00.