Open Source Software for Java
XWiki
Developed for more than 10 years, XWiki is a long standing project trusted by individuals and high profile corporations. XWiki is a free and open source Wiki software written in Java and released under the GNU Lesser General Public License. XWiki provides a WYSIWYG editing, OpenDocument based document import/export, semantic annotations and tagging, and advanced permissions management fit for enterprise use. The extensible XWiki platform allow you to customaize and improve your Wiki as the content, userbase or usecase grows and evolves.
Temporal Workflow
Temporal Workflow is a free and open-source workflow and automation tool. With Temporal Workflow you can build and operate resilient applications using developer friendly primitives. Focus on writing business logic instead of glue code and Temporal Workflow will take care of the rest.
SQuirreL SQL
SQuirreL SQL is a free and open-source SQL client and database administration tool. SQuirreL SQL is written in Java and uses JDBC to allow users to explore and interact with databases via a JDBC driver. With SQuirreL SQL you can manage your database through a graphical user interface where you can create and drop tables, add columns and rows, create function and query your data. The software is openly developed and released under the GNU Lesser General Public License which makes it free to use.
Elasticsearch
Elasticsearch is an open-source, highly scalable search and analytics engine written in Java. The engine is built ontop of Apache Lucene Library and has an advanced distributed model and consistent API interface. Elasticsearch allows you to store, search, and analyze huge volumes of data quickly and in near real-time with answers provided in milliseconds. Making it perfect for building full text search, analytics store, auto completer, spell checker, and alerting engines.
Flyway
Flyway provides open source, enterpise-grade version control for your database. By allowing your application to have a robust schema evulotion across all your environments, you can restasured that your applications are built safer and faster. With Flyway you can manage your database with plain old SQL and perform migrations for advanced data transformations and handling with LOBs and drop all tables, views, triggers, and more from a schema without dropping the schema itself. Flyway also integraties with cloud database provides and third-party hosting platforms such as Amazon RDS, Microsoft SQL Azure, Google Cloud SQL, Heroku, and more.
Apache Wicket
Apache Wicket is a free and open-source, Java-based component oriented web application framwork. With Apache Wicket you can quickly create web well structured, component-based web applications. Apache Wicket is used by governments, stores, universities, cities, banks, email providers across the globe.
OpenTSDB
OpenTSDB is a free and open-source distributed, scalable Time Series Database written on top of Apache HBase. OpenTSDB was designed to address a common need: store, index and serve metrics collected from computer systems such as network gear, operating systems and applications, at a large scale, and make this data easily accessible and graphable. OpenTSDB allows you to collect thousands of metrics from tens of thousands of hosts and applications, at a high rate and will never delete or downsample data and can easily store hundreds of billions of data points.
VRaptor
VRaptor is a free and open-source MVC framework written in Java. VRaptor is used to develop web applications on top of CDI (Contexts and Dependency Injection for Java EE). The framework features tools that allow developers to maintain a high productivity and a developer experience loved by many. The VRaptor community consist of seasoned developers that freely build and distribute the framework free of charge.
muCommander
muCommander is a lightweight, cross-platform file manager with a dual-pane interface. The application runs on any operating system with Java support including macOS, Windows, Linux, BSD and Solaris. Featuring a virtual filesystem with support for local volumes, FTP, SFTP, SMB, NFS, HTTP, Amazon S3, Hadoop HDFS and Bonjour. With muCommander you can quickly copy, move, rename files, create directories, email files and zip files can be modified live without the requirement of re-compressing entire archives. muCommander is released as free and open source software under the GNU General License.
Socket.io
Socket.IO is a free and open-source JavaScript library that can be used for building realtime web applications. The library consists of two parts, a server-side library for Node.js and a client-side library that runs in the browser.