Please suggest any missing open-source projects in the comments. I will update the list to include them.
- Apache Commons IO (commons-io) – The Apache Commons IO library contains utility classes, stream implementations, file filters, file comparators, endian transformation classes, and much more.
- Apache Commons Lang (commons-lang) – Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang’s hierarchy, or are considered to be so standard as to justify existence in java.lang.
- Apache Commons Codec (commons-codec) – The Apache Commons Codec package contains simple encoder and decoders for various formats such as Base64 and Hexadecimal. In addition to these widely used encoders and decoders, the codec package also maintains a collection of phonetic encoding utilities.
- Apache Commons Collections (commons-collections) – he Apache Commons Collections package contains types that extend and augment the Java Collections Framework.
- Apache Commons BeanUtils (commons-beanutils) – Apache Commons BeanUtils provides an easy-to-use but flexible wrapper around reflection and introspection.
- Apache Commons Pool (commons-pool) – The Apache Commons Pool open source software library provides an object-pooling API and a number of object pool implementations. Version 2 of Apache Commons Pool contains a completely re-written pooling implementation compared to the 1.x series. In addition to performance and scalability improvements, version 2 includes robust instance tracking and pool monitoring. Version 2 requires JDK level 1.6 or above.
- Apache Commons Configuration (commons-configuration) – The Commons Configuration software library provides a generic configuration interface which enables a Java application to read configuration data from a variety of sources.
- Guava: Google Core Libraries for Java – The Guava project contains several of Google’s core libraries that we rely on in our Java-based projects: collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and so forth.
- Guice – Guice (pronounced ‘juice’) is a lightweight dependency injection framework for Java 6 and above, brought to you by Google. github.com/google/guice
- Spring Framework – The Spring Framework provides a comprehensive programming and configuration model for modern Java-based enterprise applications — on any kind of deployment platform. A key element of Spring is infrastructural support at the application level: Spring focuses on the “plumbing” of enterprise applications so that teams can focus on application-level business logic, without unnecessary ties to specific deployment environments.
- Joda-Time – Joda-Time is the widely used replacement for the Java date and time classes prior to Java SE 8. www.joda.org/joda-time/
- Plexus-Utils – A collection of various utility classes to ease working with strings, files, command lines, XML and more.
- H2 – H2 is an embeddable RDBMS written in Java. h2database.com
- Apache Derby – Apache Derby, an Apache DB subproject, is an open source relational database implemented entirely in Java and available under the Apache License, Version 2.0.
- HSQLDB – HSQLDB is a relational database engine written in Java, with a JDBC driver, conforming to ANSI SQL:2011. A small, fast, multithreaded engine and server with memory and disk tables, LOBs, transaction isolation, multiversion concurrency and ACID.
- commons-dbcp – Commons-DBCP provides database connection pooling services.
- Hadoop – The Apache™ Hadoop® project develops open-source software for reliable, scalable, distributed computing.
- Hibernate – Hibernate ORM is a component/library providing Object/Relational Mapping (ORM) support to applications and other components/libraries. It is also provides an implementation of the JPA specification, which is the standardized Java specification for ORM. See Hibernate.org for additional information.
- Elasticsearch – Open Source, Distributed, RESTful Search Engine www.elastic.co/products/elasticsearch
- Ant – Ant is a Java based build tool. In theory it is kind of like “make” without makes wrinkles and with the full portability of pure java code.
- Maven – Apache Maven is a software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project’s build, reporting and documentation from a central piece of information.
- java-jwt – An implementation of JSON Web Tokens developed against
- Bukkit – The Minecraft Mod API bukkit.org
- Microsoft/Malmo – Project Malmo is a platform for Artificial Intelligence experimentation and research built on top of Minecraft. We aim to inspire a new generation of research into challenging new problems presented by this unique environment.
- Apache Log4j 2 – a logging library for Java.
- Commons-logging – Apache Commons Logging is a thin adapter allowing configurable bridging to other, well known logging systems.
- logback – The reliable, generic, fast and flexible logging framework for Java. logback.qos.ch
- JUnit – A programmer-oriented testing framework for Java.
- FEST-Assert provides a fluent interface for assertions.
- findbugs – Find Bugs in Java Programs
- jetty – Jetty is a lightweight highly scalable java based web server and servlet engine. Our goal is to support web protocols like HTTP, HTTP/2 and WebSocket in a high volume low latency way that provides maximum performance while retaining the ease of use and compatibility with years of servlet development.
- GWT – GWT is a development toolkit for building and optimizing complex browser-based applications.
- Apache HttpComponents/HttpClient – The Apache HttpComponents™ project is responsible for creating and maintaining a toolset of low level Java components focused on HTTP and associated protocols.