# ff4j/ff4j

Feature Flags for Java made easy

Repository: https://github.com/ff4j/ff4j
Canonical: https://ross.abutalabs.com/products/ff4j
Homepage: http://ff4j.github.io
Language: Java
License: Apache-2.0
License Family: permissive
Topics: feature, toggle, flipping
Last push: 2026-08-13T18:50:09+00:00

## Health v2 (maintenance only)
Score: 85/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 97, release rhythm 60, longevity 100
- inputs: {"age_days": 4820, "days_push": 20, "days_rel": 30, "gap_med": null, "n_releases_24m": 1}
- flags: prerelease_only
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1449, forks 288 (observed 2026-08-28T04:04:45.702839+00:00)

## What it is
FF4J is a Java library implementing the Feature Toggle pattern, letting teams enable and disable features at runtime without redeployments. It supports role- and strategy-based toggling, AOP annotations, monitoring dashboards, an audit trail, a web console, a CLI, and 20+ database backends for storing feature state.

## Use cases
- toggle features at runtime without redeploying my java app
- run canary releases with role-based feature access
- avoid nested if statements with annotation-driven feature flags
- store feature flags in redis or another database
- audit who toggled features and when
- monitor feature usage with metrics and dashboards
- manage feature flags from a web console or cli

## When to choose
- you need feature flags in a Java/JVM application
- you want runtime toggling with role-based or strategy-based access control
- you need a self-hosted solution with many storage backends and a built-in admin console
- you use Spring or Spring Boot and want starter/AOP integration

## When to avoid
- you need a multi-language or SaaS-hosted feature flag platform
- your stack is not on the JVM
- you only need simple environment-based config without runtime toggling

## Facets
- artifact type: library
- maturity: active
- function: feature-flags, configuration-management, monitoring, middleware
- domain: developer-tools, backend, web-development
- platform: jvm, self-hosted
- tags: feature-toggle, feature-flipping, canary-release, aop, spring-boot-starter, web-console, audit-trail, devops, spring

## Member repositories
- ff4j/ff4j (main) score 85

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:04:45.702839+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 2026-08-30T04:35:59.863214+00:00, confidence not recorded.
  - readme: https://github.com/ff4j/ff4j (fetched 2026-08-28T04:04:45.702839+00:00, sha c83e17becf37)
  - homepage: http://ff4j.github.io (fetched 2026-08-29T11:45:32.989976+00:00, sha cbce03119baf)
- Data as of 2026-08-30T08:39:29.467469+00:00.