Awesome DB

Aerospike Database Server – flash-optimized, in-memory, nosql database

AlchemyDB is now Aerospike

Fast columnar store for analytics with PostgreSQL website

Facebook's branch of the Oracle MySQL v5.6 database

Very fast embedded key/value store with full ACID semantics.

Free & open source, high-performance, distributed memory object caching system

website

The Mongo Database http://www.mongodb.org/

Redis is an in-memory database that persists on disk. The data model is key-value, but many different kind of values are supported: Strings, Lists, Sets, Sorted Sets, Hashes website

This is a version of Redis patched to implement NDS (the Naive Disk Store). Documentation on this feature is contained within README.nds.

An open-source distributed JSON document database with a pleasant and powerful query language. http://www.rethinkdb.com

Embedded key-value store for fast storage http://rocksdb.org

A completely embedded, full-featured relational database in a few 100k that you can include right into your project.

SSDB - A fast NoSQL database, an alternative to Redis http://ssdb.io

TokuDB is a high-performance, write optimized, compressing, transactional storage engine for MySQL and MariaDB

TokuMX is a high-performance, concurrent, compressing, drop-in replacement engine for MongoDB

MySQL fork maintained and used at Twitter https://github.com/twitter/mysql/wiki

VoltDB is a horizontally-scalable, in-memory SQL RDBMS designed for applications that have extremely high read and write throughput requirements.

Pulsedb is a time series database server and library.

Riak is a decentralized datastore from Basho Technologies.

A low-level key/value database for Go.

A home-grown disk-backed key-value store.

An in-memory key:value store/cache (similar to Memcached) library for Go, suitable for single-machine applications.

An implementation of the LevelDB key/value database in the Go.

Groupcache is a caching and cache-filling library, intended as a replacement for memcached in many cases.

Scalable datastore for metrics, events, and real-time analytics

Ledisdb is a high performance NoSQL like Redis based on LevelDB.

Roshi is a large-scale CRDT set implementation for timestamped events.

Sky is an open source database used for flexible, high performance analysis of behavioral data.

Your NoSQL database powered by Golang.

Cassandra is a partitioned row store. Rows are organized into tables with a required primary key.

Open Source, Distributed, RESTful Search Engine website

LMDB for Java, which is a very fast embedded key/value store with full ACID semantics.

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.http://www.mapdb.org

Neo4j is the world’s leading Graph Database.

OrientDB is an Open Source NoSQL DBMS with the features of both Document and Graph DBMSs.

Distributed Graph Database http://titandb.io

An open source clone of Amazon's Dynamo. website

Apache CouchDB™ is a database that uses JSON for documents,JavaScript for MapReduce indexes, and regular HTTP for its API [website] (http://couchdb.apache.org/)

MongoDB is a document database that provides high performance, high availability, and easy scalability. Documents (objects) map nicely to programming language data types. Embedded documents and arrays reduce need for joins. Dynamic schema makes polymorphism easier. [website] (https://www.mongodb.org/)

A list of papers essential to understanding databases and building new data systems

BlinkDB: Sub-Second Approximate Queries on Very Large Data [website] (http://blinkdb.cs.berkeley.edu/)

An in-memory embedded database engine for NET/Mono

A linq enabled document database for .NET http://ayende.com/Blog/