Message Queues
3 open source tools compared. Sorted by stars — scroll down for our analysis.
| Tool | Stars | Velocity | Score |
|---|---|---|---|
 Pulsar Distributed pub-sub messaging system | 15.2k | +8/wk | 79 |
 RabbitMQ Open source message broker | 13.6k | +14/wk | 76 |
 Redpanda Kafka-compatible streaming, 10x faster, no ZooKeeper | 11.9k | +38/wk | 67 |
Our Analysis
Pulsar is Apache's answer to Kafka, handling both messaging patterns (pub/sub and queuing) in one system. The key difference: Pulsar separates compute from storage, so you can scale message brokers and storage independently. For teams that have hit Kafka's operational ceiling, that architecture matters. Apache Foundation, Java-based. Multi-tenancy is built in; namespaces and topics can be isolated per team without running separate clusters. Supports both streaming (like Kafka) and queuing (like RabbitMQ) patterns in the same system. Geo-replication works across data centers out of the box. Fully open source, Apache 2.0. StreamNative offers a managed Pulsar cloud starting around $0.10/GB ingested, but self-hosting is the primary path. Self-hosting is where the ops burden hits. Pulsar needs ZooKeeper (or the newer metadata store) plus BookKeeper for storage. Minimum production setup is 3 brokers + 3 bookies + 3 ZK nodes. That's 9 machines before you process a single message. Solo or small teams: use NATS or RabbitMQ unless you specifically need multi-tenancy or geo-replication. Medium teams (10-50): Pulsar makes sense if you're outgrowing simpler solutions. Large: this is where Pulsar shines. The catch: the operational complexity is real. If you don't need multi-tenancy or tiered storage, Kafka is simpler to run and has a larger ecosystem of tooling and connectors.
RabbitMQ has been reliably passing messages between services since 2007. It sits between your services and makes sure messages get delivered, even if the receiving service is temporarily down. It's a post office for your backend. Service A drops a message in a queue, Service B picks it up when it's ready. RabbitMQ handles routing, retries, and ordering so you don't have to. It supports multiple messaging patterns: simple queues, pub/sub (one message to many consumers), routing by topic, and RPC. The management UI is good: you can see queue depths, message rates, and consumer health at a glance. Self-hosted is free under the Mozilla Public License. CloudAMQP offers managed hosting starting at $0 (free tier: 1M messages/month, limited connections) up to $500+/mo for production clusters. AWS, GCP, and Azure all offer managed RabbitMQ too. The catch: RabbitMQ uses Erlang, which makes it incredibly reliable but painful to debug when something goes wrong at the system level. For simple job queues, it's overkill; BullMQ or Sidekiq are lighter. For high-throughput event streaming (millions of events/sec), Kafka or Redpanda are better suited.