# square/otto

An enhanced Guava-based event bus with emphasis on Android support.

Repository: https://github.com/square/otto
Canonical: https://ross.abutalabs.com/products/square-otto
Homepage: http://square.github.io/otto/
Language: Java
License: Apache-2.0
License Family: permissive
Archived: true
Last push: 2018-12-17T16:07:14+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 35, longevity 100
- inputs: {"age_days": 5180, "days_push": 2816, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 5113, forks 827 (observed 2026-08-28T04:09:10.777789+00:00)

## What it is
Otto is an enhanced Guava-based event bus library for Java, specialized for Android, that decouples application components via synchronous publish/subscribe communication. It is officially deprecated in favor of RxJava/RxAndroid.

## Use cases
- decouple android app components with an event bus
- publish and subscribe to typed events in java
- replace callbacks with event-driven communication
- communicate between fragments and services on android

## When to choose
- maintaining a legacy Android project already using Otto
- you need a tiny synchronous Guava-style event bus on the JVM

## When to avoid
- starting a new Android project (use RxJava, RxAndroid, or coroutines Flow instead)
- you need asynchronous or threaded event dispatch
- you need an actively maintained library

## Facets
- artifact type: library
- maturity: abandoned
- function: message-queue, middleware
- domain: mobile-development, android-tools, developer-tools
- platform: jvm
- tags: event-bus, pub-sub, guava, deprecated, android

## Member repositories
- square/otto (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:10.777789+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 2026-08-29T18:02:08.661162+00:00, confidence not recorded.
  - readme: https://github.com/square/otto (fetched 2026-08-28T04:09:10.777789+00:00, sha e006194eff59)
  - homepage: http://square.github.io/otto/ (fetched 2026-08-29T08:56:50.244965+00:00, sha e01e3f38b846)
- Data as of 2026-08-30T08:39:29.467469+00:00.