Apache Kafka 3.0 Release Highlights and New Features

Apache Kafka is a widely used distributed open‑source streaming platform that originated as a message queue and has evolved into a mature event‑stream processing system. Version 3.0.0 brings a substantial set of new capabilities and API changes.

Key updates include the deprecation of Java 8 and Scala 2.12 support (to be removed in version 4.0), the introduction of KRaft as a built‑in consensus mechanism replacing ZooKeeper, and default enabling of the strongest delivery guarantees for producers (acks=all and idempotence).

Several client‑side improvements are added: the OffsetFetch and FindCoordinator requests are optimized, MirrorMaker 2 gains more flexible configuration while MirrorMaker 1 is deprecated, and the AdminClient now supports fetching offsets for multiple consumer groups in a single request.

Kafka Connect receives enhancements such as a new API to restart connectors and tasks in one call, removal of internal key/value converter properties, default enabling of connector client config overrides, and inclusion of connector log context in Log4j configurations.

Kafka Streams sees extensive changes: KRaft metadata snapshots, new producer ID generation, default consumer session timeout increase, expanded OffsetFetch API, support for multiple group coordinator resolution, removal of old message formats (v0/v1), addition of List<T> serialization, improvements to task metadata, new methods in ProcessorContext, updated windowed SerDe configuration, deprecation of the default 24‑hour grace period, and many API clean‑ups (TaskId, TaskMetadata, ThreadMetadata). The default replication factor for Streams now follows the broker default.

Additional updates include enhancements to the streams‑application‑reset tool, new KIP‑735 default consumer session timeout, and various other KIP‑driven improvements across the platform.