Kafka vs Apache Pulsar

Apache Pulsar is a messaging system whose brokers store no messages durably; a separate cluster of storage nodes, called bookies, stores them. Pulsar's documentation calls the broker "a stateless component," and states that "a BookKeeper cluster consisting of one or more bookies handles persistent storage of messages." The current release line is Pulsar 5.0, a long-term support release.

Kafka takes the other approach. Each Kafka broker stores the partitions it serves on its own disks, and the controllers that manage cluster metadata run inside Kafka itself