The Apache Pulsar team is proud to announce Apache Pulsar version 5.0.0-M1.
5.0.0-M1 is a milestone release for the upcoming Pulsar 5.0 LTS release, made to gather user feedback early. It is not meant for production use cases, since breaking changes can be introduced between the milestone releases and the final Pulsar 5.0 LTS release. Pulsar is a highly scalable, low latency messaging platform running on commodity hardware. It provides simple pub-sub semantics over topics, guaranteed at-least-once delivery of messages, automatic cursor management for subscribers, and cross-datacenter replication. What's new in 5.0, previewed in this milestone: - Scalable Topics: a new kind of topic, addressed with the topic:// scheme, that sizes itself to its actual load. The broker splits hot key-range segments and merges cold ones at runtime, with no downtime and without breaking per-key ordering -- so there is no partition count to choose up front. (PIP-460, PIP-466, PIP-468, PIP-473, PIP-475, PIP-483) - A new V5 Java client (pulsar-client-v5): a clean-slate redesign with three purpose-built consumers (Stream, Queue, Checkpoint). It works against your existing topics, and a consumer can subscribe to an entire namespace. Scalable topics are available only through the V5 API. The classic client API remains fully supported. - Oxia is now the recommended metadata store for new clusters, with a live, zero-downtime migration from ZooKeeper. ZooKeeper remains fully supported; the etcd backend is removed in 5.0. (PIP-454, PIP-462, PIP-469) - Other notable changes: structured (slog-style) logging (PIP-467), IO connectors moved to a dedicated repository (PIP-465), the javax.* to jakarta.* namespace migration (PIP-472), and a move from Maven to Gradle for the build (PIP-463). Read the full announcement for details and how to try it: https://pulsar.apache.org/blog/2026/06/23/announcing-apache-pulsar-5-0-m1/ For Pulsar release details and downloads, visit: https://pulsar.apache.org/download Release Notes are at: https://pulsar.apache.org/release-notes/versioned/pulsar-5.0.0-M1/ We would like to thank the contributors that made the release possible. Regards, The Pulsar Team
