Apache ZooKeeper

Apache ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services for distributed systems. It provides a hierarchical key-value store (znodes), watches for change notifications, ephemeral nodes for presence detection, and sequential nodes for leader election and distributed locking. ZooKeeper exposes a Java/C client API and an HTTP Admin Server API for monitoring and management. It is widely used by Kafka, Hadoop, HBase, Storm, and other distributed systems.

Apache ZooKeeper publishes 5 APIs on the APIs.io network, including Cluster API, Configuration API, Health API, and 2 more. Tagged areas include Configuration Management, Distributed Coordination, Leader Election, Service Discovery, and Open Source.

The Apache ZooKeeper catalog on APIs.io includes 1 Spectral governance ruleset.

Apache ZooKeeper’s developer surface includes documentation, developer portal, getting-started guide, release notes, support, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub

46.0/100 developing ▬ flat Agent 28/100 agent aware Full breakdown ↓
scored 2026-07-28 · rubric v0.6

AccessFreemium

6 APIs 7 Features 5 Use Cases

Configuration ManagementDistributed CoordinationLeader ElectionService DiscoveryOpen Source

Kin Score

Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6

Composite quality — 46.0/100 · developing

Contract Quality 12.3 / 25

Developer Ergonomics 7.8 / 20

Commercial Clarity 10.0 / 20

Operational Transparency 6.2 / 13

Governance 3.3 / 12

Discoverability 6.5 / 10

Agent readiness — 28/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/apache-zookeeper: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 6

Individual APIs this provider publishes, each with its own machine-readable definition.

Rate Limits 1

Documented rate limits and quota policies.

Apache Zookeeper Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Apache Zookeeper Finops

FINOPS

Features 7

Notable capabilities this provider offers.

Hierarchical Namespace

Tree-structured znode namespace similar to a filesystem for organized configuration storage.

Watch Notifications

Client watches on znodes trigger one-time callbacks on change events for reactive patterns.

Ephemeral Nodes

Nodes that disappear when the creating client session expires for presence detection.

Sequential Nodes

Auto-incrementing sequential znodes for implementing distributed queues and leader election.

Atomic Operations

Compare-and-set and multi-operation batches for consistent distributed state updates.

ACL Security

Per-znode access control lists for authentication and authorization of znode operations.

Observer Mode

Read-only observer servers for scaling read throughput without affecting write quorum.

Scroll for all 7

AGENTIC

Use Cases 5

What developers build with this provider.

Leader Election

Distributed leader election using ephemeral sequential znodes for coordination.

Distributed Configuration Management

Centralized configuration storage with watch-based change notification to services.

Service Registry and Discovery

Service registration and lookup using ephemeral znodes as presence indicators.

Distributed Locking

Distributed mutex and read/write locks using ephemeral sequential znode recipes.

Cluster Coordination

Kafka broker coordination, HBase region server management, and Hadoop NameNode fencing.

Integrations 6

Pre-built integrations with other platforms and tools.

Apache Kafka

ZooKeeper (legacy) for Kafka broker metadata and controller election (replaced by KRaft).

Apache HBase

ZooKeeper for HBase region server coordination and master election.

Apache Hadoop

ZooKeeper for HDFS NameNode HA fencing and YARN ResourceManager HA.

Apache Storm

ZooKeeper for Storm Nimbus coordination and worker heartbeat tracking.

Apache Solr

ZooKeeper for SolrCloud cluster coordination, configuration, and leader election.

Apache Curator

High-level ZooKeeper client with recipes for common distributed patterns.

Resources

Get Started 2

Portal, sign-up, and the first successful call

Portal

Portal

GettingStarted

GettingStarted

Documentation 1

Reference material describing how the API behaves

Documentation

Documentation

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

SpectralRules

SpectralRules

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubRepository

GitHubRepository

Python Kazoo Client

SDKs

Node.js Client

SDKs

Access & Security 2

Authentication, authorization, and security posture

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

ReleaseNotes

ReleaseNotes

Support

Support

Commercial 1

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

Source (apis.yml)

aid: apache-zookeeper
name: Apache ZooKeeper
description: Apache ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed
  synchronization, and providing group services for distributed systems. It provides a hierarchical key-value store (znodes),
  watches for change notifications, ephemeral nodes for presence detection, and sequential nodes for leader election and distributed
  locking. ZooKeeper exposes a Java/C client API and an HTTP Admin Server API for monitoring and management. It is widely
  used by Kafka, Hadoop, HBase, Storm, and other distributed systems.
type: Index
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
position: Consumer
access: 3rd-Party
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/apache-zookeeper.png
tags:
- Configuration Management
- Distributed Coordination
- Leader Election
- Service Discovery
- Open Source
created: '2026-03-16'
modified: '2026-05-19'
url: https://raw.githubusercontent.com/api-evangelist/apache-zookeeper/refs/heads/main/apis.yml
specificationVersion: '0.19'
apis:
- aid: apache-zookeeper:apache-zookeeper-client-api
  name: Apache ZooKeeper Client API
  description: The ZooKeeper client API provides Java and C language bindings for distributed coordination operations. Operations
    include create (create znodes), delete, exists (check existence), getData, setData, getChildren, getACL, setACL, and multi
    (batch operations). Watch mechanisms notify clients of znode changes. Curator is the recommended high-level Java client
    with recipes for distributed locks, leader elections, service discovery, and caches.
  humanURL: https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html
  tags:
  - Java
  - C
  - Coordination
  - Leader Election
  properties:
  - type: Documentation
    url: https://zookeeper.apache.org/doc/current/zookeeperProgrammers.html
  - type: APIReference
    url: https://zookeeper.apache.org/doc/current/apidocs/zookeeper-server/
  - type: SDKs
    url: https://search.maven.org/search?q=org.apache.zookeeper
    title: Java Maven SDK
  - type: SDKs
    url: https://curator.apache.org/
    title: Apache Curator (High-Level Java Client)
- aid: apache-zookeeper:apache-zookeeper-cluster-api
  name: Apache ZooKeeper Cluster API
  description: Cluster and ensemble information
  humanURL: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
  baseURL: http://localhost:8080/commands
  tags:
  - Cluster
  properties:
  - type: OpenAPI
    url: openapi/apache-zookeeper-cluster-api-openapi.yml
  - type: Documentation
    url: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
- aid: apache-zookeeper:apache-zookeeper-configuration-api
  name: Apache ZooKeeper Configuration API
  description: Server configuration information
  humanURL: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
  baseURL: http://localhost:8080/commands
  tags:
  - Configuration
  properties:
  - type: OpenAPI
    url: openapi/apache-zookeeper-configuration-api-openapi.yml
  - type: Documentation
    url: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
- aid: apache-zookeeper:apache-zookeeper-health-api
  name: Apache ZooKeeper Health API
  description: Server health checks
  humanURL: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
  baseURL: http://localhost:8080/commands
  tags:
  - Health
  properties:
  - type: OpenAPI
    url: openapi/apache-zookeeper-health-api-openapi.yml
  - type: Documentation
    url: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
- aid: apache-zookeeper:apache-zookeeper-monitoring-api
  name: Apache ZooKeeper Monitoring API
  description: Server statistics and metrics
  humanURL: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
  baseURL: http://localhost:8080/commands
  tags:
  - Monitoring
  properties:
  - type: OpenAPI
    url: openapi/apache-zookeeper-monitoring-api-openapi.yml
  - type: Documentation
    url: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
- aid: apache-zookeeper:apache-zookeeper-watches-api
  name: Apache ZooKeeper Watches API
  description: ZooKeeper watch information
  humanURL: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
  baseURL: http://localhost:8080/commands
  tags:
  - Watches
  properties:
  - type: OpenAPI
    url: openapi/apache-zookeeper-watches-api-openapi.yml
  - type: Documentation
    url: https://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_4lw
common:
- type: AgenticAccess
  url: agentic-access/apache-zookeeper-agentic-access.yml
- type: VulnerabilityDisclosure
  url: security/apache-zookeeper-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/apache-zookeeper-domain-security.yml
- type: GitHubRepository
  url: https://github.com/apache/zookeeper
- type: Documentation
  url: https://zookeeper.apache.org/doc/current/
- type: Portal
  url: https://zookeeper.apache.org/
- type: GettingStarted
  url: https://zookeeper.apache.org/doc/current/zookeeperStarted.html
- type: ReleaseNotes
  url: https://github.com/apache/zookeeper/releases
- type: Support
  url: https://zookeeper.apache.org/lists.html
- type: TermsOfService
  url: https://www.apache.org/licenses/
- type: SpectralRules
  url: rules/apache-zookeeper-spectral-rules.yml
- type: SDKs
  url: https://pypi.org/project/kazoo/
  title: Python Kazoo Client
- type: SDKs
  url: https://www.npmjs.com/package/node-zookeeper-client
  title: Node.js Client
- type: Features
  data:
  - name: Hierarchical Namespace
    description: Tree-structured znode namespace similar to a filesystem for organized configuration storage.
  - name: Watch Notifications
    description: Client watches on znodes trigger one-time callbacks on change events for reactive patterns.
  - name: Ephemeral Nodes
    description: Nodes that disappear when the creating client session expires for presence detection.
  - name: Sequential Nodes
    description: Auto-incrementing sequential znodes for implementing distributed queues and leader election.
  - name: Atomic Operations
    description: Compare-and-set and multi-operation batches for consistent distributed state updates.
  - name: ACL Security
    description: Per-znode access control lists for authentication and authorization of znode operations.
  - name: Observer Mode
    description: Read-only observer servers for scaling read throughput without affecting write quorum.
- type: UseCases
  data:
  - name: Leader Election
    description: Distributed leader election using ephemeral sequential znodes for coordination.
  - name: Distributed Configuration Management
    description: Centralized configuration storage with watch-based change notification to services.
  - name: Service Registry and Discovery
    description: Service registration and lookup using ephemeral znodes as presence indicators.
  - name: Distributed Locking
    description: Distributed mutex and read/write locks using ephemeral sequential znode recipes.
  - name: Cluster Coordination
    description: Kafka broker coordination, HBase region server management, and Hadoop NameNode fencing.
- type: Integrations
  data:
  - name: Apache Kafka
    description: ZooKeeper (legacy) for Kafka broker metadata and controller election (replaced by KRaft).
  - name: Apache HBase
    description: ZooKeeper for HBase region server coordination and master election.
  - name: Apache Hadoop
    description: ZooKeeper for HDFS NameNode HA fencing and YARN ResourceManager HA.
  - name: Apache Storm
    description: ZooKeeper for Storm Nimbus coordination and worker heartbeat tracking.
  - name: Apache Solr
    description: ZooKeeper for SolrCloud cluster coordination, configuration, and leader election.
  - name: Apache Curator
    description: High-level ZooKeeper client with recipes for common distributed patterns.
maintainers:
- FN: Kin Lane
  email: info@apievangelist.com