1. 2009. apache/cassandra. https://github.com/apache/cassandra
2. 2009. mongodb/mongo. https://github.com/mongodb/mongo
3. 2009. redis/redis. https://github.com/redis/redis
4. 2012. prometheus/prometheus. https://github.com/prometheus/prometheus
5. 2013. etcd-io/etcd. https://github.com/etcd-io/etcd