1. Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.

  2. In-Memory NoSQL DB

  3. A fast, embeddable, in-memory key/value database for Go with custom indexing and geospatial support

  4. KeyDB is fast NoSQL database with full compatibility for Redis APIs, clients, and modules.

  5. Aerospike is a high-performing NoSQL database supporting high transaction volumes with low latency.

  6. High-performance, distributed memory object caching system

  7. Clustering and highly scalable data distribution platform for Java

  8. Database for real-time transactions and analytics.

  9. In-memory JavaScript Datastore with Persistence

  10. In-memory relational DBMS capable of supporting millions of database operations per second

  11. High performance, in-memory storage engine for time series data (by Facebook)