Apache Pulsar is an open-source distributed pub-sub messaging system
This is one of the best overviews on Pulsar with comparisons to Kafka: <a href="https://jack-vanlightly.com/blog/2018/10/2/understanding-how-apache-pulsar-works" rel="nofollow">https://jack-vanlightly.com/blog/2018/10/2/understanding-how...</a>