1. Atomix: A reactive java framework for building fault-tolerant distributed systems. https://atomix.io/
2. Bft-smart: High-performance byzantine fault-tolerant state machine replication. http://bft-smart.github.io/library/
3. etcd: A distributed, reliable key-value store for the most critical data of a distributed system. https://etcd.io/
4. Jgroups - a toolkit for reliable messaging. http://www.jgroups.org/
5. jgroups-raft: Implementation of the raft consensus protocol in jgroups. http://belaban.github.io/jgroups-raft/