This list of Free Database Server,Database Engines and Database Software you can use it for free or free for non commercial use.
Ingres is a proven, high-performance open source relational database solution that offers the scalability, integration and flexibility to leverage information resources across a wide range of platforms, including Linux, UNIX, Windows and OpenVMS.
ScimoreDB Distributed SQL database is free shared-nothing clustered database system . The Database server have been designed to take advantage of parallelization over multiple servers, achieving a near linear scalability for OLTP applications. Supporting up to 512 PC's in a single database cluster, ScimoreDB offers value in terms of speed, functionality and cost.TScimoreDB Server is an extremely reliable Enterprise Database. With features such as ACID with full commit, rollback, crash recovery and row level locking, it allows you to build secure, bussiness-critical application. Support T-SQL language enable you to create your own custom and potentially intricate bussiness logic.
Perst is an object-oriented embedded database for applications that need to deal with persistent data. There are two implementations of Perst - pure Java and pure C# (C Sharp).
H2 is a SQL database engine. Available as Java library and as native executable (using GCJ). Clustering, embedded and server mode, disk based or in-memory operation. JDBC and (partially) ODBC APIs are supported. Support for transactions, referential integrity, triggers, subqueries, views, and encryption. A browser based console application is included. H2 stands for 'Hypersonic 2' and is written by original author of Hypersonic SQL.
HSQLDB is the leading SQL relational database engine written in Java. It has a JDBC driver and supports a rich subset of ANSI-92 SQL (BNF tree format) plus SQL 99 and 2003 enhancements. It offers a small, fast database engine which offers both in-memory and disk-based tables and supports embedded and server modes. Additionally, it includes tools such as a minimal web server, in-memory query and management tools and a number of demonstration examples.
Microsoft SQL Server 2005 Express Edition
SQL Server Express is a version of SQL Server 2005 designed to helps developers build robust and reliable applications by providing a powerful database that is also free and easy to use.
db4o (database for objects) is the open source object database for Java and .NET. It is free software available under the GPL and also under a commercial license. It can persist any native object with a single line of code and allows you to experience true object-orientation. Features include: ACID transactions, query-by-example, S.O.D.A. query API and automatic class schema recognition, small footprint.
Sybase ASE Express Edition for Linux
ASE Express Edition is limited to use of one CPU, 5GB of data storage and 2GB of RAM.
IBM Cloudscape V10.0
IBM Cloudscape V10.0 is a pure, open source-based Java relational database management system that can be embedded in Java programs and used for online transaction processing (OLTP).
SQLite is a small C library that implements a self-contained, embeddable, zero-configuration SQL database engine
SimpleSQL is designed to be a simple to use relational database, for Java, C++, JDBC, PHP, ActiveX, etc.
SQLMemTable is a fast in-memory database system. Key features: no BDE, no dlls required, SQL support, BLOB compression, fast indexes, import/export, Unicode, comprehensive help. SQLMemTable Personal is free for personal use. Any company must order SQLMemTable Com, Pro, Team4, Team8 or Enterprise to use it in its projects
Berkeley DB is an open-source database system made by Sleepycat Software. It is available in several different distributions including a java beta version. You can use them freely if the the complete source code for your application is available and freely redistributable under reasonable conditions. Otherwise you can purchase a license. See the website for licensing information.
Firebird is an OpenSource database environment formerly known as Borland Interbase Version 6. Features include full SQL compliancy, stored procedures, and other advance database features.
ObjectDB for Java/JDO
ObjectDB for Java/JDO is a powerful Object Database for Java. It is specially designed to handle efficiently databases of various sizes, from a few KBs to hundreds of GBs, in both embedded database mode and client server mode. As a pure Java Database, ObjectDB for Java/JDO is written entirely in Java, and it is compliant with the new Java Data Objects (JDO) standard.
MySQL database server and standard clients
MySQL is available for many platforms and you can download the server and client software as well as a MySQL ODBC diver and a bunch of other MySQL tools from this page.
PostgreSQL is an open source relational database management system and runs on many platforms. You can download the latest release as well as a conversion utility (MySQL to PostgreSQL) from this page.
hsqldb is a relational database engine written in Java, with a JDBC driver, supporting a rich subset of ANSI-92 SQL (BNF tree format). It offers a small (less than 160k), fast database engine which offers both in memory and disk based tables. Embedded and server modes are available. Additionally, it includes tools such as a minimal web server, in-memory query and management tools (can be run as applets) and a number of demonstration examples. (100% Java Database)
GNU SQL Server
SQL Server is a free portable multiuser relatational database management system. It supports the full SQL89 dialect and has some extensions from SQL92. It provides multiuser access and transaction isolation based on predicative locks. The working OS: UNIX. The working language: C . It also uses RPC, shared memory and message queues.
The Mariposa distributed database management system is an ongoing research project at the University of California at Berkeley. It allows DBMSs which are far apart and under different administrative domains to work together to process queries. Runs on Digital Equipment Alpha running DEC OSF/1 3.2 (with gcc and cc).
Dxstore Database System
The Dxstore Database System is a database management system for Linux, FreeBSD, and other operating systems. In the tradition of dbm/ndbm, it is distributed as an embeddable C or C++ library and shares with them the model of a database as a collection of key/value pairs
DiamondBase is a C++ database engine which is available for free non commercial use, and is negotiable for commercial use.