# spotify/mobius

A functional reactive framework for managing state evolution and side-effects.

Repository: https://github.com/spotify/mobius
Canonical: https://ross.abutalabs.com/products/mobius
Homepage: https://spotify.github.io/mobius/
Language: Java
License: Apache-2.0
License Family: permissive
Topics: android, java, functional-reactive-programming, mobius, state-management
Last push: 2026-08-07T08:54:04+00:00

## Health v2 (maintenance only)
Score: 73/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 96, release rhythm 28, longevity 100
- inputs: {"age_days": 3148, "days_push": 26, "days_rel": 629, "gap_med": 44.5, "n_releases_24m": 3}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1263, forks 105 (observed 2026-08-28T04:04:10.439663+00:00)

## What it is
Mobius is a functional reactive framework from Spotify for managing state evolution and side-effects, based on a unidirectional data flow loop. It ships as a pure Java core with add-ons for Android UIs, RxJava 1-3, and Kotlin Coroutines.

## Use cases
- manage app state with unidirectional data flow on Android
- separate side-effects from state updates in a mobile app
- make UI state logic unit-testable
- connect RxJava or coroutines to a state loop
- structure an Android app with MVI-style architecture

## When to choose
- you build Android apps in Java or Kotlin and want a production-proven state framework
- you need strict separation of state transitions from side-effects for testability
- you already use RxJava or Kotlin Coroutines and want integration modules

## When to avoid
- you need a cross-platform or iOS state framework
- you prefer Compose-first state management or a lighter unidirectional-flow library
- your project targets non-JVM platforms

## Facets
- artifact type: framework
- maturity: stable
- function: state-management, web-framework
- domain: mobile-development, android-tools, developer-tools
- platform: jvm
- tags: functional-reactive-programming, unidirectional-data-flow, mvvi, rxjava, kotlin-coroutines, testability, android

## Member repositories
- spotify/mobius (main) score 73

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:10.439663+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 2026-08-30T05:04:11.405787+00:00, confidence not recorded.
  - readme: https://github.com/spotify/mobius (fetched 2026-08-28T04:04:10.439663+00:00, sha 46ed34f091c9)
  - homepage: https://spotify.github.io/mobius/ (fetched 2026-08-29T12:16:18.753682+00:00, sha 8e52cb8b934e)
- Data as of 2026-08-30T08:39:29.467469+00:00.