Apache S2Graph
Apache S2Graph is a graph database designed to handle transactional graph processing at scale. Its REST API allows you to store, manage and query relational information using edge and vertex representations in a fully asynchronous and non-blocking manner. Initial contributed by Kakao Inc.
This code base is retained for historical interest only, please visit Apache Incubator Repo for latest one https://github.com/apache/incubator-s2graph