Apache Pulsar vs ZeroMQ

Apache Pulsar is a free, open-source distributed messaging and streaming platform built for cloud use. It supports message consumption with less than 10 ms latency and up to one million unique topics in a cluster. Configurable replication across geographic regions and automatic client failover to healthy clusters support multi-region deployments. Tenants and policies control access to data and actions, and can isolate brokers to limit noisy-neighbor effects. Maintained client libraries are available for Java, Go, Python, C++, Node.js, and C#. Built-in connectors move data to and from systems including Kafka, RabbitMQ, MySQL, PostgreSQL, MongoDB, Cassandra, and Elasticsearch. Pulsar Functions process messages with user-defined logic in Java, Python, or Go. Tiered storage can offload data from BookKeeper to blob storage such as S3 for unlimited retention. It can run in Docker or Kubernetes, with a Helm chart for Kubernetes. Encryption, authentication, and authorization are available but are not enabled by default. The 5.0.0-M2 milestone is for early testing and feedback, not production use.

ZeroMQ is a free, open-source asynchronous messaging library for developers building distributed or concurrent applications. A system using it can run without a dedicated broker, with patterns such as publish-subscribe, request-reply and client-server. It carries messages over transports including TCP, in-process and inter-process communication, multicast and WebSocket. The project lists language bindings and libraries for C, C++, C#, Dart, Erlang, F#, Go, Haskell, Java, Node.js, Perl, Python, Ruby, Rust and Zig. Supported protocols also include ZMTP, UDP, IPC, PGM, NORM and TIPC, and delivery guarantees are configurable. The project says libzmq and many bindings support PLAIN and CURVE security mechanisms. libzmq is licensed under MPL-2.0; the project says closed-source commercial applications do not need a separate commercial license. Installation guidance covers macOS, Linux distributions and Windows. One documented constraint affects Go’s zmq4 wrapper: it requires ZeroMQ and development files to be installed and cannot be cross-compiled. ZeroMQ is self-hosted and listed at free.