GDBM - GNU dbm (or GDBM, for short) is a library of database functions that use extensible hashing and...
Berkeley DB - Berkeley DB (BDB) is a software library that provides a high-performance embedded database for...
Tokyo Cabinet - Tokyo Cabinet: a modern implementation of DBM
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
SQLite - SQLite Home Page
Apache Cassandra - The Apache Cassandra database is the right choice when you need scalability and high availability without compromising performance.