25+ Alternative & Open Source Database Engines

It can be one of the popular databases below:

or even simpler ones like XML, text, etc.

It is understandable why these databases are frequently used; they are well-documented, have a community behind them, integrated with most popular CMSs', easy-to-use, offered by most of the hosting companies ,etc..

But there are also many other databases which are getting popular day-by-day & may have advantages over what you're already using.

Here are 25+ open source alternative databases that you may consider using in your next project:

MongoDB

It is an open source, high-performance, scalable, schema-free & document-oriented (JSON-like data schemas) database.

There are ready to use drivers for most popular programming languages like PHP,Python, Perl, Ruby, JavaScript, C++ + more.

Hypertable

Hypertable is a high performance distributed data storage systemdesigned to support applications requiring maximum performance, scalability, and reliability.

It is modeled after Google's BigTable and mostly focuses on large-scale datasets.

Apache CouchDB

A document-oriented database that can be queried and indexed in a MapReduce fashion using JavaScript.

CouchDB offers a RESTful JSON API which can be accessed from any environment allowing HTTP requests

Neo4j

It is an embedded, disk-based, and fully transactional Java persistence engine that stores data structured in graphs rather than tables.

Neo4j offer a massive scalability. It can handle graphs of several billion nodes/relationships/properties on a single machine and can be scaled across multiple machines.

Riak

Riak is a very ideal database for web applications as it combines:

a decentralized key-value store
a flexible map/reduce engine
a friendly HTTP/JSON query interface.

Oracle Berkeley DB

It is an embeddable database engine that provides developers with fast, reliable, local persistence with zero administration.

Oracle Berkeley DB is a library that links directly into your application & enables you to make simple function calls rather than sending messages to a remote server for a better performance.

Apache Cassandra

Cassandra is a highly scalable second-generation distributed databasethat is used by giants like Facebook, Digg, Twitter, Cisco & more..

It aims to provide a consistent, fault-tolerant & highly available environment for storing data.

Memcached

Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.

It is intended for use in speeding up dynamic web applications by alleviating database load.

Firebird

Firebird is a relational database that can run on Linux, Windows & various UNIX platforms.

It offers high performance and powerful language support for stored procedures and triggers.

Redis

Redis is an advanced fast key-value database written in C which can be used like memcached, in front of a traditional database, or on its own.

It has support for many programming languages & used by popular projects like GitHub or Engine Yard.

There is also a PHP client named Rediska for managing Redis databases.

HBase

HBase is a distributed & column-oriented store which can also be called as the Hadoop database.

The project aims to host very large tables like "billions of rows, millions of columns".

It has a REST-ful web service gateway that supports XML, Protobuf, and binary data encoding options.

Keyspace

It is a consistently replicated, fault-tolerant key-value store that works in Windows OS.

Keyspace offers high availability by masking server/network failures & appearing as a single, highly available service.

4store

4store is a database storage and query engine that holds RDF data.

It is written in ANSI C99, designed to run on UNIX-like systems & offers a high performance, scalable & stable platform.

MariaDB

MariaDB is a backward compatible, drop-in replacement branch of the MySQL® Database Server.

It includes all major open source storage engines + the Maria storage engine.

Drizzle

It is a fork of MySQL that focuses on being a reliable database optimized for Cloud and Net applications.

HyperSQL

It is a SQL relational database engine written in Java.

HyperSQL offers a small & fast database engine which has in-memory and disk-based tables, supports embedded/server modes.

Also, it has tools such as a command line SQL tool & GUI query apps.

Others

Gladius (PHP flat-file database)
CloudStore
OpenQM (multivalue database)
ScarletDME (multivalue database)
SmallSQL (Java Desktop SQL Database Engine)
LucidDB
HyperGraphDB (graph database)
InfoGrid (graph database)
Apache Derby
hamsterdb
H2 Database
EyeDB
txtSQL
db4o
Tokyo Cabinet
Project Voldemort