Free software programmed in Java

OpenOffice.org is an open-source office productivity software suite. It originated from the proprietary StarOffice, developed by Star Division, which was acquired by Sun Microsystems in 1999. Sun open-sourced the software in July 2000 as a free alternative to Microsoft Office, and released OpenOffice.org version 1.0 on 1 May 2002.

LibreOffice () is a free and open-source office productivity software suite developed by The Document Foundation (TDF). It was created in 2010 as a fork of OpenOffice.org, itself a successor to StarOffice. The suite includes applications for word processing (Writer), spreadsheets (Calc), presentations (Impress), vector graphics (Draw), database management (Base), and formula editing (Math). It supports the OpenDocument format and is compatible with other major formats, including those used by Microsoft Office.

software development environment

privacy-focused encrypted messaging app

GeoGebra (a portmanteau of geometry and algebra) is an interactive geometry, algebra, statistics and calculus application, intended for learning and teaching mathematics and science from primary school to university level. GeoGebra is available on multiple platforms, with apps for desktops (Windows, macOS and Linux), tablets (Android, iPad and Windows) and web. As of 2025, it is owned by Indian edutech firm Byju's.

free and open-source office suite

NetBeans is an integrated development environment (IDE) for Java. NetBeans allows applications to be developed from a set of modular software components called modules. NetBeans runs on Windows, macOS, Linux and Solaris. In addition to Java development, it has extensions for other languages like PHP, C, C++, HTML5, and JavaScript. Applications based on NetBeans, including the NetBeans IDE, can be extended by third party developers.

an implementation of the Java Servlet, JavaServer Pages, Java Expression Language and Java WebSocket technologies

distributed data processing framework

OmegaT is a computer-assisted translation tool written in the Java programming language. It is free software originally developed by Keith Godfrey in 2000, and is currently developed by a team led by Aaron Madlon-Kay.

software tool for automating software build processes

The Invisible Internet Project (I2P) is an anonymous network layer (implemented as a mix network) that allows for censorship-resistant, peer-to-peer communication. Anonymous connections are achieved by encrypting the user's traffic (by using end-to-end encryption), and sending it through a volunteer-run network of roughly 55,000 computers distributed around the world. Given the high number of possible paths the traffic can transit, a third party watching a full connection is unlikely. The software that implements this layer is called an "I2P router", and a computer running I2P is called an "I2

Vuze (previously Azureus) is a BitTorrent client used to transfer files via the BitTorrent protocol. Vuze is written in Java, and uses the Azureus Engine. In addition to downloading data linked to .torrent files, Azureus allows users to view, publish and share original DVD and HD quality video content. Content is presented through channels and categories containing TV shows, music videos, movies, video games, series and others.

open-source virtual globe developed by NASA

Jitsi (from , "wires") is a collection of free and open-source multiplatform voice (VoIP), video conferencing and instant messaging applications for the Web platform, Windows, Linux, macOS, iOS, iPadOS, watchOS, and Android. The Jitsi project began with the Jitsi Desktop (previously known as SIP Communicator). With the growth of WebRTC, the project team focus shifted to the Jitsi Videobridge for allowing web-based multi-party video calling. Later the team added Jitsi Meet, a full video conferencing application that includes web, Android, iOS, iPadOS, and watchOS clients. Jitsi also operates me

suite of machine learning software written in Java

LimeWire was a free peer-to-peer file sharing client for Windows, Mac OS X, Linux, and Solaris. Created by Mark Gorton in 2000, it was most prominently a tool used for the download and distribution of pirated materials, particularly pirated music.

software development kit (SDK) for the development and deployment of rich Internet applications

continuous integration tool

JUnit is a test automation framework for the Java programming language. JUnit is often used for unit testing, and is one of the xUnit frameworks.

Elasticsearch is a source-available search engine developed by Elastic. It is based on Apache Lucene and provides a distributed, multitenant-capable full-text search engine with an HTTP web interface and schema-free JSON documents. Official clients are available in Java, C#, PHP, Python, Ruby, and other languages. According to the DB-Engines ranking, Elasticsearch is the most popular enterprise search engine.

Hyphanet (until mid-2023: Freenet) is a peer-to-peer platform for censorship-resistant, anonymous communication. It uses a decentralized distributed data store to keep and deliver information, and has a suite of free software for publishing and communicating on the Web without fear of censorship. Both Freenet and some of its associated tools were originally designed by Ian Clarke, who defined Freenet's goal as providing freedom of speech on the Internet with strong anonymity protection.

Jmol is computer software for molecular modelling of chemical structures in 3 dimensions. It is an open-source Java viewer for chemical structures in 3D. The name originated from [[Java (programming language)|[J]ava]] (the programming language) + [mol]ecules, and also the mol file format.

open source data stream processing platform

Compiere (pronounced KOM-pyeh-reh, "to accomplish, complete, fulfill" in Italian) is an open-source ERP and CRM business solution for small and medium-sized enterprises (SME) in distribution, retail, service, and manufacturing. Compiere is distributed by Consona Corporation and through a partner network, who are a collection of trained and authorized business partners.

open-source web application framework

Apache Log4j is a Java-based logging utility originally written by Ceki Gülcü. It is part of the Apache Logging Services, a project of the Apache Software Foundation. Log4j is one of several Java logging frameworks.

WildFly, formerly known as JBoss AS, or simply JBoss, is an application server written by JBoss, now developed by Red Hat. WildFly is written in Java and implements the Java Platform, Enterprise Edition (Java EE) specification. It runs on multiple platforms.

YaCy (pronounced “ya see”) is a free distributed search engine built on the principles of peer-to-peer (P2P) networks, created by Michael Christen in 2003. The engine is written in Java and distributed on several hundred "YaCy-peer" computers, .

FreeCol is a 4X video game, a clone of ''Sid Meier's Colonization. FreeCol is free and open source software released under the GNU GPL-2.0-or-later. In 2023, the FreeCol'' project reached its 1.0 release, after twenty years of development.

OpenJDK (Open Java Development Kit) is a free and open-source implementation of the Java Platform, Standard Edition (Java SE). It is the result of an effort Sun Microsystems began in 2006, four years before the company was acquired by Oracle Corporation. The implementation is licensed under the GNU General Public License 2 with a linking exception, preventing components that linked to the Java Class Library becoming subject to the terms of the GPL license. OpenJDK is the official reference implementation of Java SE since version 7, and is the most popular distribution of the JDK.

free web-based team code collaboration tool

Free and open-source, distributed, wide column store, NoSQL database management system.

OpenRefine is an open-source desktop application for data cleanup and transformation to other formats, an activity commonly known as data wrangling. It is similar to spreadsheet applications, and can handle spreadsheet file formats such as CSV, but it behaves more like a database.

FreeMind is a free mind mapping application written in Java, which is further developed by the fork Freeplane. FreeMind itself was last updated in 2014. FreeMind is licensed under the GNU General Public License Version 2. It provides extensive export capabilities. It runs on Microsoft Windows, Linux, and macOS via the Java Runtime Environment.

jEdit is a free software text editor available under GPL-2.0-or-later. It is written in Java and runs on any operating system with Java support, including BSD, Linux, macOS and Windows.

LanguageTool is a free and open-source grammar, style, and spell checker, and all its features are available for download. The LanguageTool website connects to a proprietary sister project called LanguageTool Premium (formerly LanguageTool Plus), which provides improved error detection for English and German, as well as easier revision of longer texts, following the open-core model.

Ghidra ( ) is a free and open source reverse engineering tool developed by the National Security Agency (NSA) of the United States. The binaries were released at the RSA Conference in March 2019; the source code was published one month later on GitHub. Ghidra is seen by many security researchers as a competitor to IDA Pro. The software is written in Java using the Swing framework for the GUI. The decompiler component is written in C++, and is therefore usable in a stand-alone form.

FrostWire is a free and open-source BitTorrent client first released in September 2004, as a fork of LimeWire. It was initially very similar to LimeWire in appearance and functionality, but over time developers added more features, including support for the BitTorrent protocol. In version 5, support for the Gnutella network was dropped entirely, and FrostWire became a BitTorrent-only client.

HSQLDB (Hyper SQL Database) is a relational database management system written in Java. It has a JDBC driver and supports a large subset of SQL-92, SQL:2008, SQL:2011, and SQL:2016 standards. It offers a fast, small (around 1300 kilobytes in version 2.2) database engine which offers both in-memory and disk-based tables. Both embedded and server modes are available.

JDownloader is a donationware download manager, written in Java, which allows automatic download of groups of files from one-click hosting sites. JDownloader supports the use of premium accounts. Some parts of the code are open-source. As a popular software tool used in Europe, in December 2009 the program's website was in the top 1000 visited websites of Spain. German online magazine Chip.de designated it "newcomer of the year" in 2009, after it ranked among the top 50 most downloaded applications, with over half a million downloads in a year.

DSpace is an open source repository software package typically used for creating open access repositories for scholarly and/or published digital content. While DSpace shares some feature overlap with content management systems and document management systems, the DSpace repository software serves a specific need as a digital archives system, focused on the long-term storage, access and preservation of digital content. The optional DSpace registry lists more than three thousand repositories all over the world.

In computing, GeoServer is an open-source server written in Java that allows users to share, process and edit geospatial data. Designed for interoperability, it publishes data from any major spatial data source using open standards. GeoServer has evolved to become an easy method of connecting existing information to virtual globes such as Google Earth and NASA World Wind as well as to web-based maps such as OpenLayers, Leaflet, Google Maps and Bing Maps. GeoServer functions as the reference implementation of the Open Geospatial Consortium Web Feature Service standard, and also implements the W

Neo4j is a graph database management system (GDBMS) developed by Neo4j Inc.

GlassFish is an open-source Jakarta EE platform application server project started by Sun Microsystems, then sponsored by Oracle Corporation, and now living at the Eclipse Foundation and supported by OmniFish, Fujitsu and Payara. The supported version under Oracle was called Oracle GlassFish Server. GlassFish is free software and was initially dual-licensed under two free software licences: the Common Development and Distribution License (CDDL) and the GNU General Public License (GPL) with the Classpath exception. After having been transferred to Eclipse, GlassFish remained dual-licensed, but

open-source content-management system

OSGi is an open specification and open source project under the Eclipse Foundation.

Orbot is a free proxy app that provides anonymity on the Internet for users of the Android and iOS operating systems. It allows traffic from apps such as web browsers, email clients, map programs, and others to be routed via the Tor network.

web server written in Java

Liferay, Inc., is an open-source company focused on enterprise portal technology. The company has its headquarters in Diamond Bar, California, United States.

JRuby is an implementation of the Ruby programming language atop the Java Virtual Machine, written largely in Java. It is free software released under a three-way EPL/GPL/LGPL license. JRuby is tightly integrated with Java to allow the embedding of the interpreter into any Java application with full two-way access between the Java and the Ruby code (similar to Jython for the Python language).

open-source enterprise-search platform

TuxGuitar is a free and open-source tablature editor, which includes features such as tablature editing, score editing, and import and export of Guitar Pro gp3, gp4, and gp5 files. In addition, TuxGuitar's tablature and staff interfaces function as basic MIDI editors.

relational database management system

Open-source web framework written in Scala

OpenCms is an open-source content management system written in Java. It is distributed by Alkacon Software under the LGPL license. OpenCms requires a JSP Servlet container such as Apache Tomcat.

KNIME (), the Konstanz Information Miner, is a data analytics, reporting and integrating platform. KNIME integrates various components for machine learning and data mining through its modular data pipelining "Building Blocks of Analytics" concept. A graphical user interface and use of Java Database Connectivity (JDBC) allows assembly of nodes blending different data sources, including preprocessing (extract, transform, load (ETL)), for modeling, data analysis and visualization with minimal, or no, programming. It is free and open-source software released under a GNU General Public License.

web application framework written in Java

JavaCC (Java Compiler Compiler) is an open-source parser generator and lexical analyzer generator written in the Java programming language.

The Visualization Toolkit (VTK) is a free software system for 3D computer graphics, image processing and scientific visualization.