# apache/zookeeper

Apache ZooKeeper

Repository: https://github.com/apache/zookeeper
Canonical: https://ross.abutalabs.com/products/zookeeper
Homepage: https://zookeeper.apache.org
Language: Java
License: Apache-2.0
License Family: permissive
Topics: zookeeper, database, hacktoberfest, java, apache, consensus, coordination, zab, key-value, distributed-database, distributed-systems, service-discovery, configuration-management, distributed-configuration
Last push: 2026-08-25T18:22:34+00:00

## Health v2 (maintenance only)
Score: 77/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 35, longevity 100
- inputs: {"age_days": 6368, "days_push": 8, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 12795, forks 7330 (observed 2026-08-28T04:10:59.824800+00:00)

## What it is
Apache ZooKeeper is a high-performance, fault-tolerant coordination service for distributed applications, exposing a hierarchical key-value namespace with ordered, replicated updates via the ZAB consensus protocol. It provides off-the-shelf primitives such as naming, configuration management, synchronization, and group services used by systems like Kafka, Hadoop, and HBase.

## Use cases
- implement leader election among distributed workers
- build distributed locks and mutexes across a cluster
- register and discover live service instances dynamically
- propagate configuration changes to all nodes with watches
- track cluster membership and node liveness in real time
- synchronize phased computations with barriers and queues
- store small amounts of strongly consistent metadata for a distributed system

## When to choose
- you need battle-tested coordination primitives (locks, leader election, group membership) with strong consistency
- you operate distributed systems like Kafka, Hadoop, or HBase that depend on ZooKeeper
- you need a small, highly reliable replicated key-value store with total ordering of updates
- you want watches to push configuration changes without polling

## When to avoid
- you need to store large volumes of data or serve as a general-purpose database
- you want a modern consensus store with a richer API like etcd or Consul
- your workload requires horizontal write scaling rather than a single coordinated quorum
- you only need simple caching or messaging without coordination guarantees

## Facets
- artifact type: service
- maturity: stable
- function: database, service-discovery, configuration-management, caching, message-queue
- domain: microservices, databases, infrastructure-as-code, backend
- platform: jvm, windows, cross-platform, self-hosted
- tags: coordination, consensus, zab, leader-election, distributed-locks, key-value-store, apache, cluster-management, devops, linux, macos, docker

## Member repositories
- apache/zookeeper (main) score 77

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:59.824800+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 2026-08-29T17:13:47.038265+00:00, confidence not recorded.
  - readme: https://github.com/apache/zookeeper (fetched 2026-08-28T04:10:59.824800+00:00, sha 50623b235264)
  - homepage: https://zookeeper.apache.org (fetched 2026-08-29T08:09:55.817853+00:00, sha 0768e26c6a5f)
  - site_page: https://zookeeper.apache.org/releases (fetched 2026-08-29T08:09:55.822473+00:00, sha 3a537c94c329)
  - site_page: https://zookeeper.apache.org/doc/r3.9.5 (fetched 2026-08-29T08:09:55.824420+00:00, sha b4db9ee39ab6)
  - site_page: https://zookeeper.apache.org/doc/r3.8.6 (fetched 2026-08-29T08:09:55.826244+00:00, sha 230f9cf3cf36)
  - site_page: https://zookeeper.apache.org/doc/r3.7.2 (fetched 2026-08-29T08:09:55.828162+00:00, sha b103e2f29246)
- Data as of 2026-08-30T08:39:29.467469+00:00.