Garnet is a remote cache-store from Microsoft Research that offers strong performance (throughput and latency), scalability, storage, recovery, cluster sharding, key migration, and replication features. Garnet can work with existing Redis clients.
Fast persistent recoverable log and key-value store + cache, in C# and C++.
MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine.
ZoneTree is a persistent, high-performance, transactional, ACID-compliant ordered key-value database and LSM-tree storage engine for .NET.