Message Queues

7 open source tools compared. Sorted by stars — scroll down for our analysis.

Tool	Stars	Velocity	Language	License	Score
Redis In-memory data store for caching, queues, and real-time apps	73.5k	—	C	—	72
Kafka Distributed event streaming platform	32.2k	+89/wk	Java	Apache License 2.0	79
NATS High-performance cloud and edge native messaging system	19.4k	+55/wk	Go	Apache License 2.0	79
Pulsar Distributed pub-sub messaging system	15.2k	+10/wk	Java	Apache License 2.0	79
RabbitMQ Open source message broker	13.5k	+19/wk	Erlang	—	69
Redpanda Kafka-compatible streaming, 10x faster, no ZooKeeper	11.9k	+40/wk	C++	—	67
ZeroMQ High-performance async messaging	10.8k	+13/wk	C++	Mozilla Public License 2.0	76

Our Analysis

Redis73.5k★

Redis is the in-memory data store that powered half the internet's caching layers — until the license drama. In 2024, Redis Ltd. switched from BSD to SSPL, blocking cloud providers. In 2025, they added AGPL with Redis 8. The tech is still excellent. The trust is broken. Valkey is the Linux Foundation-backed BSD fork — already the default on AWS ElastiCache, Google Memorystore, and Akamai. It's the direct replacement. Dragonfly is a C++ rewrite claiming 25x throughput on the same hardware. KeyDB (Snap) is multi-threaded Redis that uses all CPU cores. If you're starting fresh, use Valkey. Same protocol, same commands, BSD license, backed by every major cloud provider. If you need raw speed, evaluate Dragonfly. The catch: Redis 8 under AGPL means any network-facing modifications require source disclosure. The enterprise features (SSO, LDAP, admin UI) are now paywalled in AIStor. And the community edition is in maintenance mode — no new features, selective security fixes. Redis the technology is great. Redis the company made it complicated.

Kafka32.2k★

Kafka is the backbone of event-driven architecture at scale — a distributed streaming platform that handles millions of messages per second with durable, replayable event logs. If your system needs to process events in real-time and you can't afford to lose a single one, Kafka is the industry standard. Skip this if you're a solo founder building an MVP. Kafka is enterprise infrastructure that requires ZooKeeper (or KRaft), brokers, and ops expertise. RabbitMQ is simpler for traditional message queuing at 50-100K messages/second. NATS is lighter and faster for microservice pub/sub. Redis Streams works for small-scale event streaming. The catch: Kafka is operationally heavy. Running it yourself means managing brokers, partitions, consumer groups, and storage. Confluent Cloud removes the ops burden but costs real money. And Kafka's learning curve is steep — topics, partitions, offsets, and consumer group rebalancing will take weeks to grok. For most indie projects, you don't need Kafka. You need a simple queue.

NATS19.4k★

NATS is messaging stripped to the metal. A single Go binary that handles pub/sub, request/reply, and durable streaming (JetStream) with sub-millisecond latency and a tiny resource footprint. It runs everywhere from cloud clusters to Raspberry Pis. JetStream adds at-least-once delivery and persistence without losing NATS's simplicity. Compared to Kafka (higher throughput, much more complex), NATS is easier to operate and faster for most workloads. Compared to RabbitMQ (more routing features, heavier), NATS is lighter and scales horizontally better. Compared to Redis Pub/Sub (simpler but no persistence), JetStream fills the gap. Use this when you need fast, simple messaging for microservices without the operational weight of Kafka or RabbitMQ. Skip this if you need Kafka's exactly-once semantics or RabbitMQ's advanced routing patterns. The catch: NATS core is at-most-once delivery by default — messages can be lost. JetStream adds durability but with different semantics to learn. The ecosystem is growing but still smaller than Kafka's or RabbitMQ's. Apache 2.0 license.

Pulsar15.2k★

Pulsar is what you reach for when Kafka's architecture starts fighting your requirements. It separates compute (brokers) from storage (BookKeeper), so you can scale each independently. Multi-tenancy is built-in, not bolted on. Geo-replication works across data centers. And it handles both streaming and queue patterns natively — no choosing between Kafka and RabbitMQ. If you're building cloud-native, multi-tenant, or geo-distributed messaging systems, Pulsar's architecture genuinely fits better than Kafka. Kafka is still king for raw throughput — 15x faster writes and a massive ecosystem. RabbitMQ is the battle-tested choice for traditional task queues with complex routing. NATS is the lightweight option for microservices pub-sub. The catch: Pulsar is complex. You're running brokers plus BookKeeper plus ZooKeeper (being removed) — that's three distributed systems to manage. Kafka's ecosystem is 10x larger: more connectors, more tooling, more engineers who know it. And Pulsar's throughput, while good, doesn't match Kafka's at the high end. For most teams, Kafka's operational simplicity wins.

RabbitMQ13.5k★

RabbitMQ is the message broker that just works. For 15+ years, it's been the default choice for task queues, async processing, and service-to-service communication. Complex routing, priority queues, dead-letter exchanges, and acknowledgment patterns — RabbitMQ handles the messaging patterns that Kafka was never designed for. If you're building traditional request-response systems, worker queues, or need flexible message routing, RabbitMQ is battle-tested and boring in the best way. Kafka is for event streaming and log aggregation at massive scale — different tool, different job. NATS is the ultra-lightweight option for simple pub-sub. Redis Streams works for in-memory messaging when durability isn't critical. The catch: RabbitMQ is written in Erlang, which makes operational debugging an adventure. Clustering and high availability are more complex than the docs suggest — mirrored queues were replaced by quorum queues for good reason. And RabbitMQ's throughput caps around 10-100K messages per second, which is fine for most apps but doesn't compete with Kafka at scale.

Redpanda11.9k★

Redpanda is Kafka without the JVM, without ZooKeeper, and without the operational nightmare. A C++ rewrite that's Kafka API-compatible, so your existing producers and consumers work unchanged. Up to 10x faster with a single binary deployment. If you need event streaming and have been dreading the Kafka learning curve, Redpanda is the shortcut. Kafka is the standard but demands a team to operate. NATS is lighter and simpler but not Kafka-compatible. RabbitMQ is great for task queues but not event streaming. Confluent Cloud is managed Kafka with enterprise pricing. Best for teams that need Kafka's capabilities without Kafka's operational burden. The single-binary deployment is a genuine differentiator — one process, no JVM tuning, no ZooKeeper. The catch: the license changed — the community edition is limited, and the full features require an enterprise license. At extreme scale, Kafka's ecosystem (Connect, Streams) is more mature. And "Kafka-compatible" isn't "Kafka-identical" — edge cases in client behavior exist. Test your specific workload before migrating.

ZeroMQ10.8k★

ZeroMQ is messaging for people who think RabbitMQ is too much software. It's a socket library that gives you distributed messaging patterns (pub/sub, request/reply, push/pull) without a broker, without a daemon, without configuration files. Just link the library and go. If you're building distributed systems that need low-latency message passing between components — think microservices talking to each other, worker pipelines, or real-time data feeds — ZeroMQ is the lightweight option. RabbitMQ and Kafka are the heavyweights with persistence, delivery guarantees, and management UIs. NATS is the modern alternative with similar simplicity but better clustering. The power is the pattern library. Pub/sub, dealer/router, pipeline — these are battle-tested distributed patterns you'd otherwise implement badly yourself. Bindings exist for every language. The catch: no broker means no persistence and no delivery guarantees by default. If a subscriber is offline, messages are gone. MPL-2.0 license means modifications to ZeroMQ itself must be shared. And the documentation, while extensive, assumes you understand distributed systems concepts.