Open Source Java Database Engines/Servers

Firebird RDBMS offers ANSI SQL features & runs on Linux, Windows & several Unix platforms. Features excellent concurrency & performance & powerful stored procedure & trigger language. More information and downloads at https://firebirdsql.org/, issue tracker is https://github.com/FirebirdSQL/firebird/issues

HSQLDB is a relational database engine written in Java, with a JDBC driver, conforming to ANSI SQL:2023. A small, fast, multithreaded engine and server with memory and disk tables, LOBs, transaction isolation, multiversion concurrency and ACID.

The Lemur Project develops search engines, browser toolbars, text analysis tools, and data resources that support research and development of information retrieval and text mining software, including the Indri search engine in C++, the Galago search engine research framework in Java, the RankLib learning to rank library, ClueWeb09 and ClueWeb12 datasets and the Sifaka data mining application.

OpenRefine is a powerful Java-based tool designed to work with messy data and improve it. With OpenRefine you can load data, understand it, clean it up, transform it, reconcile it, and augment it with web services and external data. It allows you to do this all from a web browser and in the convenience and privacy of your own computer. OpenRefine keeps all data securely in your computer by running a small server on it, using your web browser to interact with it. When you're ready, then that is the only time the data will be shared outside of your computer. OpenRefine is available in over 15 languages, is cross-platform and part of the Code for Science & Society.

Mondrian is an OLAP (online analytical processing) engine written in Java. It reads from JDBC data sources, aggregates data in a memory cache, and implements the MDX language and the olap4j and XML/A APIs.

Make AI-driven decisions using your data, in real-time. At any scale, with unbeatable performance. Vespa is a full-featured text search engine and supports both regular text search and fast approximate vector search (ANN). This makes it easy to create high-performing search applications at any scale, whether you want to use traditional techniques or a modern vector-based approach. You can even combine both approaches efficiently in the same query, something no other engine can do. Recommendation, personalization and targeting involves evaluating recommender models over content items to select the best ones. Vespa lets you build applications which does this online, typically combining fast vector search and filtering with evaluation of machine-learned models over the items. This makes it possible to make recommendations specifically for each user or situation, using completely up to date information.

Conductor is an open-source, durable workflow orchestration engine designed to manage distributed systems, microservices, and AI-driven applications at internet scale. Originally built at Netflix and actively maintained by Orkes and the open-source community, Conductor simplifies complex workflow management by handling retries, failures, state persistence, and long-running process execution automatically. The platform enables developers to orchestrate AI agents, APIs, human approvals, and microservices using flexible JSON-based workflows with dynamic runtime execution. Conductor supports durable execution, deterministic orchestration, workflow replayability, and horizontal scalability, making it suitable for enterprise-grade applications and mission-critical automation. It offers polyglot worker support across languages such as Java, Python, JavaScript, Go, C#, Ruby, and Rust, allowing teams to integrate workflows into virtually any technology stack.

Moved to https://github.com/DANS-KNAW/dans-dbf-lib.

Java CSV is a small fast open source Java library for reading and writing CSV and plain delimited text files. All kinds of CSV files can be handled, text qualified, Excel formatted, etc.

db4o is the world's leading open source object database for Java and .NET. Leverage fast native object persistence, ACID transactions, query-by-example, S.O.D.A object query API, automatic class schema evolution, small size (http://developer.db4o.com)

olap4j is an open Java API for connecting to OLAP servers and writing analytic applications. Code is at https://github.com/olap4j/olap4j.

Attendance Marker Solution is the attendance marking software connected with local-based or server-based MySQL Server Engine. The connectivity and installation is very easy for use.

This project aims at creating an open source chemistry plugin / cartridge for the relational database system Oracle. Free Oracle chemistry cartridge.

The Malete database core is the new basis of OpenIsis, which has its roots in the UNESCO CDS/ISIS database. Traditionaly used in libraries; now a general purpose highspeed database.

In the Oracle database there are two PL/SQL APIs to send mails: UTL_SMTP and UTL_MAIL. But there is no package which is able to retrieve messages from a mailbox on a server. The here provided package MAIL_CLIENT closes this gap.

Anti-Plagiarism - software designed to effectively detect and thereby prevent plagiarism. It is a versatile tool to deal with World Wide Web copy-pasting information from the assignment of authorship. The goal of this program is to help reduce the impact of plagiarism on education and educational institutions. Checking documents in a format *.rtf, *.doc, *.docx, *.pdf Check the source code C, C++, C#, Java, ... Download - https://ap.km.ua/ Documentation - https://ap.km.ua/

eXist-db is a native XML database featuring efficient, index-based XQuery processing, extensions for keyword search, XUpdate support, XSLT support, XForms support, REST and tight integration with existing XML development tools. Moved to Github - https://www.github.com/exist-db/exist

TM4J is a topic map engine implemented entirely in Java. Topic maps are a standard paradigm for the interchange of knowledge structures. This project aims to produce a complete suite of tools for creating, processing and publishing topic map information.

Nextobjects is an Integrated Development Tool for Entreprise Applications. It use Turbine Torque for code generation. It is based on the Merise method.

Ozone is a fully featured, object-oriented database management system implemented in Java and distributed under the LGPL open source license. The ozone project aims to evolve a database system that allows developers to build pure object-oriented systems.

OpenVista(R) is the open-source version of VistA, an enterprise grade health care information system developed by the U.S. Veterans Affairs and deployed at 1,500 global facilities. OpenVista is a registered trademark of Medsphere Systems Corporation

Ridiculously simple, Prevayler provides transparent ACID persistence and replication for plain old Java objects. It is literally several thousand times faster than using a relational database through JDBC.

Rel is a DBMS primarily intended for educational purposes, but also suitable as a desktop DBMS or lightweight server, that implements Date and Darwen's "Tutorial D" true relational database language. Source code is available at https://github.com/DaveVoorhis/Rel

NeoDatis ODB is a new generation Object Oriented Database. ODB is a real native and transparent persistence layer for Java, .Net, Groovy, Scala and Google Android. ODB is very simple and very fast and comes with a powerful query language.

An implementation (parser/interpreter) of SPARQL, a query language for RDF data that is the current recommendation of the W3C. Allows easy cusomization of the language and plugs in to several popular RDF servers, like Sesame.