Awesome Java

A curated list of awesome Java frameworks, libraries and software. Inspired by awesome-python.

Awesome Java
Resources
Contributing

Build Tool

Tools which handle the buildcycle of an application.

Apache Maven - Declarative build and dependency management which favors convention over configuration. It's preferable to Apache Ant which uses a rather procedural approach and can be rather difficult to maintain.
Gradle - Incremental builds which are programmed via Groovy instead of declaring XML. Works well with Maven's dependency management and treats Ant scripts as first-class citizens.

Code Analysis

Tools that provide metrics and quality measurements of static code.

SonarQube - Inspection tool for code quality. It integrates with several external tools like Gradle, Jira and Jenkins and provides an overview of the metrics over time.
FindBugs - Static analysis of bytecode to find potential bugs.
Metrics - Measures the behavior of critical components.

Compiler-compiler

Tools that create parsers, interpreters or compilers.

ANTLR - Complex full-featured framework for top-down parsing.
JavaCC - More specific and slightly easier to learn. Has syntactic lookahead.

Continuous Integration

Tools which support continuously building, testing and releasing applications.

Jenkins - Provides server-based services. Often seen as the successor to Hudson, although it is still actively developed.
Travis - A hosted continuous integration service that integrates with GitHub repositories.
Shippable - Based on Docker, it provides also Bitbucket integration.

Database

Everything which simplifies interactions with the database.

JDBI - Convenient abstraction of JDBC.
jOOQ - Generates typesafe code based on SQL schema.
Liquibase - Source control for your database which can be embedded.
presto - Distributed SQL query engine for big data.

Date and Time

Libraries related to date and time.

Java 8 SE: Date and Time API - Basically, it incorporates Joda-Time.
Joda-Time - De facto standard date/time-library before Java 8.

Dependency Injection

Libraries that help to realize the Inversion of Control paradigm.

Dagger - Compile-time injection framework without reflection, mainly for Android.
Google Guice - Lightweight but powerful framework.
Spring - Only Spring Context is needed for injections.
Weld - CDI reference implementation.

Development

Integrated environments that augment the process of development at a fundamental level.

DCEVM - Modification of the JVM that allows unlimited redefinition of loaded classes at runtime.
JRebel - Instantly reloads code and configuration changes without redeploys.
RxJava - Library for composing asynchronous and event-based programs using observable sequences from the JVM.
vert.x - Polyglot event-driven application framework for the JVM.

Distributed Applications

Libraries and frameworks used to ease writing distributed and fault-tolerant applications.

Akka - Toolkit and runtime for building highly concurrent, distributed, and fault tolerant event-driven applications.
Apache Storm - Distributed realtime computation system.
Hystrix - Latency and fault tolerance library designed to isolate points of access to remote systems, services and 3rd party libraries, stop cascading failure and enable resilience in complex distributed systems where failure is inevitable.
JGroups - Toolkit for reliable messaging and creating clusters whose nodes can send messages to each other.
Apache ZooKeeper - Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.

Distribution

Tools which handle the distribution of Java applications in native formats.

Launch4j - Wraps JARs in lightweight and native Windows executables.
packr - Packs your JAR, assets and JVM for native distribution on Windows, Linux and Mac OS X.
Bintray - Version control for your binaries which handles the publishing. Can also be used with Maven or Gradle.

Document Processing

Libraries that assist with processing office document formats.

Apache POI - Supports OOXML (e.g XLSX, DOCX, PPTX) as well as OLE2 (e.g. XLS, DOC or PPT).
jOpenDocument - Processes the OpenDocument format.

GUI

Libraries to create modern graphical user interfaces.

JavaFX - The successor of Swing.
Scene Builder - Visual layout tool for JavaFX applications.

Game Development

Frameworks that support the development of games.

jMonkeyEngine - Game engine for modern 3D development.
LWJGL - Robust framework that abstracts libraries like OpenGL/CL/AL.
libGDX - All-round cross-platform, high-level framework.

High Performance

Everything about high performance computation, from collections to specific libraries.

Disruptor - Inter-thread messaging library.
fastutil - Fast and compact type-specific collections for Java.
GS Collections - Collection framework inspired by Smalltalk.
hftc - Hash sets and hash maps.
HPPC - Primitive collections.
Javalution - Library for real-time and embedded systems.
Trove - Primitive collections.

HTTP

Libraries for working with HTTP.

OkHttp - An HTTP+SPDY client for Android and Java applications.

IDE

Integrated development environments that try to simplify several aspects of development.

NetBeans - Provides integration for several Java SE and EE features starting with database access and servers to HTML5 and AngularJS.
Eclipse - Does a lot of things in the background. Noteworthy are its large amount of plugins.
IntelliJ IDEA - Supports a lot of JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.

Imagery

Libraries that assist with the cration, evaluation or manipulation of graphical images.

Picasso - Image downloading and caching library for Android.
ZXing - Multi-format 1D/2D barcode image processing library.

JVM and JDK

Various implementations of the JVM/JDK.

HotSpot - Official JVM.
JDK 9 - Early access releases of JDK 9.
OpenJDK - Open source implementation.

JSON

Libraries that simplify JSON processing.

Google Gson - Serializes Java objects to JSON and vice versa. Good performance with on-the-fly usage.
Jackson - Similar to GSON but has performance gains if you need to instantiate the library more often.

Logging

Libraries that log the behavior of an application.

Apache Log4j 2 - Complete rewrite of the previous version. Now has a powerful plugin and configuration architecture.
Logback - Founded by the same developer as Log4j and proves to be a robust logging library with interesting configuration options via Groovy.
SLF4J - Abstraction layer which is to be used with an implementation.

Machine Learning

Tools that provide specific statistical algorithms which allow to learn from data.

Apache Hadoop - Open-source software framework for storage and large-scale processing of data-sets on clusters of commodity hardware.
Apache Mahout - Scalable algorithms focused on collaborative filtering, clustering and classification.
Apache Spark - Open-source data analytics cluster computing framework.
h2o - Analytics engine for statistics over big data.
Weka - Collection of algorithms for data mining tasks ranging from pre-processing to visualization.

Messaging

Tools that help sending messages between clients to ensure protocol independency.

Apache ActiveMQ - Open-source message broker that implements JMS and converts synchronous to asynchronous communication.
Apache Kafka - High-throughput distributed messaging system.
JBoss HornetQ - Clear, concise, modular and made to be embedded.

Miscellaneous

Everything else.

Jimfs - In-memory file system.
Lanterna - Easy console text GUI library similar to curses.
Lombok - Code-generator which aims to reduce the verbosity of Java.
OpenRefine - Tool for working with messy data: cleaning it; transforming it from one format into another; extending it with web services; and linking it to databases.
RoboVM - Write native iOS apps in Java.

Natural Language Processing

Libraries that specialize on processing text.

Apache OpenNLP - Toolkit for common tasks like tokenization.
LingPipe - Toolkit for a variety of tasks ranging from POS tagging to sentiment analysis.
Mallet - Statistical natural language processing, document classification, clustering, topic modeling, etc.

Networking

Libraries for network programming.

Netty - A framework for building high performance network applications.

ORM

APIs which handle the persistence of objects.

EclipseLink - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
Hibernate - Robust and widely used with an active community.

PDF

Everything that helps with the creation of PDF files.

Apache FOP - Creates PDF from XSL-FO.
Apache PDFBox - Toolbox for creating and manipulating PDF.
JasperReports - Complex reporting engine.
DynamicReports - Simplifies JasperReports.
iText - Easy to use PDF library which creates PDF files programmatically but requires a license for commercial purposes.

Security

Libraries that handle security, authentication, authorization or session management.

Apache Shiro - Performs authentication, authorization, cryptography and session management.
Keycloak - Integrated SSO and IDM for browser apps and RESTful web services. Currently in beta but looks very promising.
PicketLink - PicketLink is an umbrella project for security and identity management for Java applications.
Spring Security - Focuses on authentication/authorization and protects against several attack vectors.

Science

Libraries for scientific computing and analysis.

JScience - Comprehensive framework of science related libraries.
JTransforms - Multithread FFT library.
Parallel Colt - Multithread high performance scientific and technical computing.
SCaVis - Environment for scientific computation, data analysis and data visualization.

Search

Engines which index documents for search and analysis.

Apache Solr - Full enterprise search engine optimized for high volume traffic.
Elasticsearch - Distributed, multitenant-capable full-text search engine with a RESTful web interface and schema-free JSON documents.

Server

Servers which are specifically used to deploy applications.

GlassFish - Open source reference implementation for Java EE sponsored by Oracle.
WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support.
Jetty - Lightweight, small server, often embedded in projects.
Apache Tomcat - Robust all-round server for Servlet and JSP.
Apache TomEE - Tomcat plus Java EE.

Template Engine

Tools which substitute expressions in a template.

Apache Velocity - Templates for HTML pages, emails or source code generation in general.
FreeMarker - General templating engine without any heavyweight or opinionated dependencies.
JavaServer Pages - Aged templating for websites with custom tag libraries.
Thymeleaf - Aims to be a substitute for JSP and works for XML files in general.

Testing

Tools that test from object to interface level including performance and other benchmarks.

AssertJ - Fluent assertions.
Apache JMeter - Functional testing and performance measurements.
Arquillian - Integration and functional testing platform with integration of Java EE containers.
Calipher - Microbenchmarking framework.
FEST - Collection of testing libraries.
Hamcrest - Framework for writing declarative assertion matchers.
JMH - Microbenchmarking.
JUnit - Testing framework.
Mockito - Creation of test double objects in automated unit tests for the purpose of TDD or BDD.
Selenium - Portable software testing framework for web applications.
TestNG - Testing framework.
VisualVM - Visual interface for viewing detailed information about Java applications while they are running on a JVM.

Utility

Libraries which provide unspecific functionality, e.g. optimized datastructures.

Apache Commons - Provides different general purpose functions like configuration, validation, collections, file upload or XML processing.
Google Guava - Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and so forth.
javatuples - Does what it says, although the concept of tuples in general is debatable.

Visualization

Libraries or frameworks which allow you to visualize data.

Processing - A project deeply rooted in visual art which allows you to program the visualization of data.

Web Crawling

Libraries that analyze the content of websites.

Apache Nutch - Highly extensible, highly scalable Web crawler for production environment.
Crawler4j - Simple lightweight alternative.
jsoup - Scrapes, parses, manipulates and cleans HTML.

Web Frameworks

Frameworks that handle the communication between the layers of an web application.

Apache Tapestry - Component oriented framework for creating dynamic, robust, highly scalable web applications in Java.
Spring - Aims to simplify the development with Java EE and provides packages for dependency injection and aspect-oriented programming.
Spring Boot - Microframework which simplifies the development of new Spring applications.
Vaadin - Event-driven framework build on top of GWT. Uses server-side architecture with Ajax on the client-side.
Google Web Toolkit - Toolbox which includes a Java-to-JavaScript compiler for client-side code, XML parser, API for RPC, JUnit integration, internationalization support and widgets for the GUI.
Grails - Groovy framework with the aim to provide a highly productive environment by favoring convention over configuration, no XML and support for mixins.
Apache Wicket - Component-based web application framework similar to Tapestry with a stateful GUI.
Play - Uses convention over configuration, hot code reloading and display of errors in the browser.
PrimeFaces - JSF framework which has a free and a commercial version with support. Provides several frontend components.
Spark - Unique framework which focuses not on complex MVC patterns but on rapid development.

REST Frameworks

Frameworks specifically for creating RESTful services.

Dropwizard - Opinionated framework for setting up modern web applications, includes Jetty, Jackson, Jersey and Metrics.
Jersey - JAX-RS reference implementation.
RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
RESTX - A lightweight REST framework with emphasis on modularity, speed and dev-friendly features (light specs compiled to unit tests and documentation, authentication needed by default, ...)
Retrofit - A type-safe REST client for Java.

Resources

Communities

Active discussions.

r/java - Subreddit for the Java community.
stackoverflow - Question/answer platform.

Influential Books

Books about Java that had a high impact and are still worth reading.

Podcasts

Something to listen to while programming.

The Java Posse

Twitter

People to follow.

Websites

Sites to read.

Contributing

Contributions are very welcome!

Please have a look at CONTRIBUTING for guidelines.

Topics which have no libraries as of yet are located in TOPICS.

binlijin/awesome-java