# apache/pulsar

Apache Pulsar - distributed pub-sub messaging system

Repository: https://github.com/apache/pulsar
Canonical: https://ross.abutalabs.com/products/pulsar
Homepage: https://pulsar.apache.org/
Language: Java
License: Apache-2.0
License Family: permissive
Topics: pulsar, pubsub, messaging, streaming, queuing, event-streaming
Last push: 2026-08-26T23:48:36+00:00

## Health v2 (maintenance only)
Score: 98/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 96, longevity 100
- inputs: {"age_days": 3718, "days_push": 7, "days_rel": 30, "gap_med": 0, "n_releases_24m": 42}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 15315, forks 3748 (observed 2026-08-28T04:11:09.640854+00:00)

## What it is
Apache Pulsar is a cloud-native, distributed pub-sub messaging and streaming platform originally developed at Yahoo and now a top-level Apache project. It combines flexible queuing and streaming semantics with multi-tenancy, geo-replication, tiered storage, and a layered architecture that scales horizontally to millions of topics and messages per second.

## Use cases
- build a distributed work queue with guaranteed message delivery
- stream events between microservices at low latency
- replicate messages across geographic regions with automatic failover
- run a multi-tenant messaging cluster for an entire organization
- process event streams with Pulsar Functions
- offload aged message data to S3 or GCS with tiered storage
- consume messages individually or as ordered streams

## When to choose
- you need both queuing and streaming semantics in one platform
- you require multi-tenancy, quotas, and access control on a shared cluster
- you need geo-replication and cluster-level failover out of the box
- you need to scale to hundreds of nodes and a million topics without data reshuffling
- you want official clients for Java, Go, Python, C++, C#, and Node.js

## When to avoid
- you need a lightweight single-node message broker for a small app
- your team cannot operate a multi-component system (broker, BookKeeper, ZooKeeper)
- you are already deeply invested in Kafka's ecosystem and tooling
- you only need simple point-to-point RPC without messaging guarantees

## Facets
- artifact type: service
- maturity: stable
- function: message-queue, streaming, rpc, auth, authorization
- domain: microservices, big-data, backend, cloud-computing
- platform: jvm, cross-platform, self-hosted, cloud
- tags: pubsub, event-streaming, geo-replication, multi-tenancy, apache, bookkeeper, tiered-storage, transactions, messaging, real-time, docker, kubernetes, linux, macos

## Member repositories
- apache/pulsar (main) score 98

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:09.640854+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 2026-08-29T17:06:22.572589+00:00, confidence not recorded.
  - readme: https://github.com/apache/pulsar (fetched 2026-08-28T04:11:09.640854+00:00, sha 0f16fc546730)
  - homepage: https://pulsar.apache.org/ (fetched 2026-08-29T08:04:16.707055+00:00, sha c5d184f39677)
  - site_page: https://pulsar.apache.org/docs/5.0.x/concepts-overview (fetched 2026-08-29T08:04:16.716572+00:00, sha 20f0d461861c)
  - site_page: https://pulsar.apache.org/docs/5.0.x (fetched 2026-08-29T08:04:16.718841+00:00, sha 1f0ac1c7f832)
  - site_page: https://pulsar.apache.org/docs/client-libraries (fetched 2026-08-29T08:04:16.720580+00:00, sha ad69e7a9b494)
  - site_page: https://pulsar.apache.org/features (fetched 2026-08-29T08:04:16.722143+00:00, sha 642d94574fb3)
- Data as of 2026-08-30T08:39:29.467469+00:00.