Used by Meta, Yahoo and Reddit, Apache Zookeeper has been a fundamental piece of open-source software for nearly two decades, having joined the Apache Foundation as a top-level project in 2008.
The service, used to speed up work across distributed processes, was built at Yahoo in the 2000s, but grew to widespread adoption, with AI search company Elastic dubbing it the “king of coordination” in 2014.
Zookeeper (ZK) also became a critical service for open-source distributed event streaming platform Apache Kafka – which required users to install ZK alongside Kafka until the latter’s 2.8.0 release in 2021, to handle distributed coordination of Kafka nodes, and metadata storage.
However, 2025 saw high-profile users like LinkedIn move its service discovery system away from ZK (citing “critical issues in scalability, compatibility, and extensibility”), and Kafka drop all its support for ZK, with one maintainer describing ZK as a “bottleneck” for operations.
What do the changes mean?
