JFreeChart is a popular open-source chart library for the Java platform. It allows developers to create a wide variety of charts, such as bar charts, line charts, pie charts, and more, which can be used in both desktop and web applications.

Hibernate is a powerful, high-performance Object-Relational Mapping (ORM) library for Java. It provides a framework for mapping an object-oriented domain model to a relational database and handles common tasks such as CRUD operations, caching, and transaction management.

Apache POI is a Java library for reading and writing Microsoft Office documents, including Word, Excel, and PowerPoint files. It allows developers to create, modify, and extract data from Office documents programmatically.

Joda-Time is a comprehensive date and time library for Java that offers a more powerful and flexible alternative to the standard Java Date and Calendar classes. It provides an improved API for handling dates, times, intervals, and durations.

Spring Boot is a part of the larger Spring Framework ecosystem. It simplifies the development of production-ready applications and microservices by providing default configurations and reducing the amount of boilerplate code required.

Guava is a set of core libraries for Java developed by Google. It includes several utilities to simplify concurrent programming, such as the ListenableFuture framework, which makes it easier to work with asynchronous operations.

Jersey is an open-source framework for developing RESTful web services in Java. It provides support for creating web services according to the REST architectural pattern and simplifies the development of RESTful applications.

Vaadin is a web application framework for Java. It provides a high-level API for creating web applications with a component-based approach, allowing developers to build rich, interactive user interfaces using Java.

Vavr (formerly known as Javaslang) is a library that brings functional programming to Java. It provides immutable data types and functional control structures, enhancing Java’s capabilities for functional programming.

JavaMail is an API that provides a platform-independent and protocol-independent framework to build mail and messaging applications. It allows Java applications to send, receive, and manipulate email messages.

Gson is a Java library developed by Google that is used to convert Java Objects into their JSON representation and vice versa. It can handle complex data structures and is commonly used for parsing and handling JSON data in Java applications.

The Java Reflection API allows for the inspection and manipulation of classes, interfaces, fields, and methods at runtime. It provides the ability to dynamically examine and modify the behavior of applications, making it a powerful tool for building flexible and dynamic code.

SecureRandom is part of the Java Security API. It provides a cryptographically strong random number generator (RNG) that is used for generating secure random values, which are crucial for security-sensitive applications.

The Spring Framework is a comprehensive framework for enterprise Java development. One of its core features is dependency injection, which allows for the decoupling of object creation and their dependencies, making the code more modular, testable, and maintainable.

JDBC (Java Database Connectivity) is an API that allows Java applications to interact with a wide range of databases. It provides methods to execute SQL queries, retrieve results, and manage database connections.

JAXB (Java Architecture for XML Binding) is a Java library that provides a standard way to convert Java objects to XML and vice versa. It simplifies the process of handling XML data by allowing developers to work with XML content through Java classes.

JUnit is a framework for writing and running tests in Java. It is widely used for unit testing, allowing developers to write and execute tests for individual units of code to ensure they work as expected.

Apache Commons Math is a library that provides tools for advanced mathematical computations and data analysis. It includes algorithms for linear algebra, statistics, random data generation, and more, making it useful for scientific and engineering applications.

iText is a library that allows developers to create and manipulate PDF documents. It is widely used for generating dynamic PDF content, such as reports, invoices, and other documents, from Java applications.

Log4j is a logging library for Java that provides a reliable, fast, and flexible framework for logging messages from applications. It is part of the Apache Logging Services and is commonly used for logging information, debugging, and tracking application behavior.

Guava is a set of core libraries for Java developed by Google. It provides a wide range of utilities and enhancements for collections, caching, primitives support, concurrency, common annotations, string processing, and more.

RxJava is a library for composing asynchronous and event-based programs using observable sequences. It is a popular choice for implementing reactive programming in Java, allowing developers to handle asynchronous events and data streams in a more declarative manner.

OSGi (Open Service Gateway initiative) is a Java framework for building modular applications. It provides a dynamic component model that allows applications to be composed of modules (bundles) that can be installed, started, stopped, updated, and uninstalled without requiring a restart.

Batik is a Java-based toolkit for applications that want to use images in the Scalable Vector Graphics (SVG) format. It allows developers to create, manipulate, and render SVG content, providing comprehensive support for this XML-based graphics format.

JavaFX is a set of graphics and media packages that enables developers to design, create, test, debug, and deploy rich client applications that operate consistently across diverse platforms. It is specifically designed for creating and managing graphical user interfaces (GUIs).