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A collection of Java frameworks, libraries and software.

This is my fork of Awesome Java and useful Java links.

Java greatness

Core utilities

Widely used libraries that you will almost always need and never want to reinvent. Proven and core dependencies for Java development

  • Guava - Collections, caching, primitives support, immutable collections, concurrency libraries, common annotations, string processing, I/O, and more. Very lightweight.
  • Apache Commons Lang String manipulation methods, basic numerical methods, object reflection, concurrency, creation and serialization and System properties. Additionally it contains basic enhancements to java.util.Date and a series of utilities dedicated to help with building methods, such as hashCode, toString and equals.
  • Apache Commons IO Library of utilities to assist with developing IO functionality. Utility classes - with static methods to perform common tasks, Input/Output Stream and Reader/Writer implementations, filters, comparators, etc.

Good reading

Build Tools

Tools which handle the build cycle and dependencies of an application.

  • Apache Maven - Declarative build and dependency management which favors convention over configuration. It might be preferable to Apache Ant which uses a rather procedural approach and can be difficult to maintain.
  • Apache Ant - Build process management with XML.
  • Bazel - Build tool from Google that builds code quickly and reliably. It's still in beta, but usable. Huge future potoential.
  • Gradle - Incremental builds which are programmed via Groovy instead of declaring XML. Works well with Maven's dependency management.

Classpath Scanning

  • ClassIndex - ClassIndex is a much quicker alternative to every run-time annotation scanning library like Reflections or Scannotations.
  • FastClasspathScanner - FastClasspathScanner is an uber-fast, ultra-lightweight classpath scanner for Java, Scala and other JVM languages.

Source control hosting / browsing

  • Gogs - A painless self-hosted Git service
  • RhodeCode - Centralized control for distributed repositories. Mercurial, Git, and Subversion under a single roof.
  • Phabricator - Phabricator is a complete set of tools for developing software. Included apps help you manage tasks and sprints, review code, host git, svn, or mercurial repositories, build with continuous integration, review designs, discuss in internal chat channels...

Continuous Integration

Tools which support continuously building, testing and releasing applications.

  • Hudson - Continuous integration server still in active development.
  • Bamboo - Atlassian's solution with good integration of their other products. You can either apply for an open-source license or buy it.
  • fabric8 - Integration platform for containers.
  • GoCD - ThoughtWork's open-source solution.
  • Jenkins - Provides server-based deployment services. Also see Blue Ocean.
  • TeamCity - JetBrain's CI solution with a free version.
  • Travis - Hosted service often used for open-source projects.
  • Concourse - Open-source. Pipelines are defined as a single declarative config file, composing together just three core concepts
  • CircleCI - A payed continuous integration and delivery platform. Very popular.

High Performance Collections And Libraries

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

  • Trove - The Trove library provides high speed regular and primitive collections for Java. Faster and uses less memory.
  • HPPC - High Performance Primitive Collections. Optimized for high performance and memory efficiency.
  • Eclipse Collections - Reduce memory footprint, usability improvements. Formerly called gs-collections.
  • Google Guava Collections - Mostly used for the immutable sets, lists, maps. Usability improvements.
  • High Scale Library - Fast, concurrent, lock-free HashMap. Linear scaling to 768 CPUs: NonBlockingHashMap, NonBlockingHashSet, etc.
  • Agrona - Data structures and utility methods that are common in high-performance applications.
  • Disruptor - Inter-thread messaging library.
  • fastutil - Fast and compact type-specific collections.
  • JCTools - Concurrency tools currently missing from the JDK.
  • Koloboke - Hash sets and hash maps.
  • ExpiringMap - A high performance, low-overhead, zero dependency, thread-safe ConcurrentMap implementation that expires entries.

JSON

Libraries for serializing and deserializing JSON to and from Java objects.

  • Gson - Serializes 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.
  • Genson - Powerful and easy to use Java to JSON conversion library.
  • JSON-io - Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer.
  • LoganSquare - JSON parsing and serializing library based on Jackson's streaming API. Outpeforms GSON & Jackson's library.

JSON Processing

Libraries for processing data in JSON format.

  • fastjson - Very fast processor with no additional dependencies and full data binding.
  • Jolt - JSON to JSON transformation tool.
  • JsonPath - Extract data from JSON using XPATH like syntax.
  • JsonSurfer - Streaming JsonPath processor dedicated to processing big and complicated JSON data.

Bytecode Manipulation

Libraries to manipulate bytecode programmatically.

  • ASM - All purpose, low level, bytecode manipulation and analysis.
  • Byte Buddy - Further simplifies bytecode generation with a fluent API.
  • Byteman - Manipulate bytecode at runtime via DSL (rules) mainly for testing/troubleshooting.
  • Javassist - Tries to simplify the editing of bytecode.
  • cglib - Bytecode generation library.

Cluster Management

Frameworks which can dynamically manage applications inside of a cluster.

  • Apache Aurora - Apache Aurora is a Mesos framework for long-running services and cron jobs.
  • Apache Mesos - Abstracts CPU, memory, storage, and other compute resources away from machines.
  • Singularity - Singularity is a Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.

Code Analysis

Tools that provide metrics and quality measurements.

  • Checkstyle - Static analysis of coding conventions and standards.
  • Codacy - Continuous static analysis, code coverage, and software metrics to automate code reviews.
  • Error Prone - Catches common programming mistakes as compile-time errors.
  • FindBugs - Static analysis of bytecode to find potential bugs.
  • jQAssistant - Static code analysis with Neo4J-based query language.
  • PMD - Source code analysis for finding bad coding practices.
  • SonarQube - Integrates other analysis components via plugins and provides an overview of the metrics over time.

Code Coverage

Frameworks and tools that enable collection of code coverage metrics for test suites.

  • Clover - Proprietary code coverage tool by Atlassian that relies on source-code instrumentation, instead of bytecode instrumentation.
  • Cobertura - Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics; GPLv2 licensed.
  • JaCoCo - Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation; prominently used by EclEmma, the Eclipse code-coverage plugin.

Code Style

  • Google Java Style Guilde - A complete definition of Google's coding standards for source code in the Java Programming Language.

Command-line Argument Parsers

Libraries that make it easy to parse command line options, arguments, etc.

  • args4j - Small library to parse command like arguments similar to javac.
  • Airline - Java annotation-based framework for parsing Git like command line structures.
  • JCommander - Command line arguments parsing framework with custom types and validation via implementing interfaces.
  • JOpt Simple - Simple parser that uses the POSIX getopt() and GNU getopt_long() syntaxes. Does not use annotations, uses a fluent API instead.

Compilers, Compiler-compiler

Frameworks that compile, help to 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.
  • Rootbeer - The Rootbeer GPU Compiler lets you use GPUs from within Java.
  • SableCC - SableCC is a parser generator which generates fully featured object-oriented frameworks for building compilers, interpreters and other text parsers. In particular, generated frameworks include intuitive strictly-typed abstract syntax trees and tree walkers.
  • parboiled - a mixed Java/Scala library providing for lightweight and easy-to-use, yet powerful and elegant parsing of arbitrary input text based on Parsing expression grammars (PEGs).

Configuration

Libraries that provide external configuration.

  • Typesafe Config - Configuration library for JVM languages.
  • owner - Reduces boilerplate of properties.

Constraint Satisfaction Problem Solver

Libraries that help on implementing optimization and satisfiability problems.

  • Choco - Off-the-shelf constraint satisfaction problem solver, which uses constraint programming techniques.
  • JaCoP - Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models.
  • OptaPlanner - Business planning and resource scheduling optimization solver.

CSV

Frameworks and libraries that simplify reading/writing CSV data.

  • opencsv - Simple CSV parser with a commercial-friendly license.
  • Super CSV - Powerful CSV parser with support for Dozer, Joda-Time and Java 8.
  • uniVocity-parsers - One of the fastest and most feature-complete CSV. Also comes with parsers for TSV and fixed width records.

Database

Everything which simplifies interactions with the database.

  • Apache Hive - Data warehouse infrastructure built on top of Hadoop.
  • Apache Phoenix - High performance relational database layer over HBase for low latency applications.
  • Chronicle Map - Efficient in-memory (opt. persisted to disk) off-heap key-value store.
  • eXist - A NoSQL document database and application platform.
  • FlexyPool - Brings metrics and failover strategies to the most common connection pooling solutions.
  • Flyway - Simple database migration tool.
  • H2 - Small SQL Database notable for its in-memory functionality.
  • HikariCP - High performance JDBC connection pool.
  • JDBI - Convenient abstraction of JDBC.
  • Jedis - A small client for interaction with redis, with methods for commands.
  • jOOQ - Generates typesafe code based on SQL schema.
  • Liquibase - Database-independent library for tracking, managing and applying database schema changes.
  • MapDB - Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.
  • Presto - Distributed SQL query engine for big data.
  • Querydsl - Typesafe unified queries.
  • Realm - Mobile database to run directly inside phones, tablets or wearables.
  • Redisson - Allows for distributed and scalable data structures on top of a Redis server.
  • Speedment - A database access library that utilizes the Java 8 Stream API for querying.
  • Vibur DBCP - JDBC connection pool library which offers advanced performance monitoring capabilities.

Data structures

Efficient and specific data structures.

  • Apache Avro - Data interchange format featuring among others: dynamic typing, untagged data, absence of manually assigned IDs.
  • Apache Orc - Fast and efficient columnar storage format for hadoop based workloads.
  • Apache Parquet - Columnar storage format based on assembly algorithms from the Dremel paper by Google.
  • Apache Thrift - Data interchange format that originated at Facebook.
  • Persistent Collection - Persistent and immutable analogue of the Java Collections Framework.
  • Protobuf - Google's data interchange format.
  • SBE - Simple Binary Encoding, one of the fastest message formats around.
  • Wire - Clean, lightweight protocol buffers.
  • Amazon Ion - Amazon Ion is a richly-typed, self-describing, hierarchical data serialization format offering interchangeable binary and text representations. The text format (a superset of JSON) is easy to read and author, supporting rapid prototyping. The binary representation is efficient to store, transmit, and skip-scan parse.
  • JavaLite ActiveJDBC - Fast ORM for agile development

Date and Time

Libraries related to handling date and time.

  • Natty Natty is a natural language date parser written in Java. Very powerful, look at the example tests.
  • PrettyTime Human time parsing library for Java
  • jchronic A port of Ruby's Chronic library to work with human and relative times.
  • Almanac Converter - Simple conversion between different calendar systems.
  • Joda-Time - De facto standard date/time-library before Java 8.
  • ThreeTenBP - Port of JSR 310 (java.time package) by the author of Joda-Time.
  • Time4J - Advanced date and time library.

Dependency Injection

Libraries that help to realize the Inversion of Control paradigm.

  • Guice - Lightweight but powerful framework that completes Dagger.
  • Spring DI - The Spring Framework provides a comprehensive programming and configuration model for modern Java-based enterprise applications.
  • Apache DeltaSpike - CDI extension framework.
  • Dagger2 - Compile-time injection framework without reflection.
  • HK2 - Light-weight and dynamic dependency injection framework.

Development and Code Generation

Augmentation of the development process at a fundamental level.

  • Lombok- Code-generator which aims to reduce the verbosity.
  • Auto - Collection of source code generators. Includes AutoValue that has immutable value classes, equals, hashCode and toString
  • Immutables - Java annotation processors to generate simple, safe and consistent value objects. Simliar to Lombok and AutoValue.
  • ADT4J - JSR-269 code generator for algebraic data types.
  • AspectJ - Seamless aspect-oriented programming extension.
  • DCEVM - Modification of the JVM that allows unlimited redefinition of loaded classes at runtime.
  • HotswapAgent - Unlimited runtime class and resource redefinition.
  • JHipster - Yeoman source code generator to create applications based on Spring Boot and AngularJS.
  • JRebel - Commercial software that instantly reloads code and configuration changes without redeploys.
  • Spring Loaded - Class reloading agent.

Caching / Distributed Caching

This has a lot of overlap with NoSQL databases.

  • Ehcache - Distributed general purpose cache.
  • Couchbase - An open-source, distributed multi-model NoSQL document-oriented database software package that is optimized for interactive applications.
  • Riak - A distributed NoSQL key-value data store that offers high availability, fault tolerance, operational simplicity, and scalability
  • Memcached - A general-purpose distributed memory caching system.
  • Redis - A data structure server. It is open-source, networked, in-memory, and stores keys with optional durability.
  • Varnish - Open source HTTP engine/reverse HTTP proxy.
  • Caffeine - High performance, near optimal caching library.

Distributed Computing

Libraries and frameworks for writing distributed and fault-tolerant applications.

  • Apache Hadoop - Storage and large-scale processing of data-sets on clusters of commodity hardware.
  • Apache Spark - Data analytics cluster computing framework.
  • Apache Storm - Realtime computation system.
  • Apache ZooKeeper - Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.
  • Axon Framework - Framework for creating CQRS applications.
  • Copycat - Fault-tolerant state machine replication framework.
  • Hazelcast - Highly scalable in-memory datagrid.
  • Hystrix - Provides latency and fault tolerance.
  • JGroups - Toolkit for reliable messaging and creating clusters.
  • Lagom - Framework for creating microservice-based systems.
  • Orbit - Virtual Actors, adding another level of abstraction to traditional actors.
  • Pinpoint - Application performance management tool.
  • Quasar - Lightweight threads and actors for the JVM.
  • DistributedLog - DistributedLog (DL) is a high performance replicated log service.
  • Named Pipes - Distributed Named Pipes http://dnpip.es

Distributed Messaging and Queues

Tools that help to send messages between clients in order to ensure protocol independency.

  • Akka - Akka Cluster provides a fault-tolerant decentralized peer-to-peer based cluster membership service with no single point of failure or single point of bottleneck. Good when you need low latency and have lots of consumers.
  • Kafka - Publish-subscribe messaging rethought as a distributed commit log. High-throughput distributed messaging system.
  • ZooKeeper - Apache Apache ZooKeeper provides a basis for many distributed structures such as locks and queues. Also used for leader election and configuration management.
  • RabbitMQ - Message-queueing. Good when message reliability is more important than latency.
  • Hazelcast - Open Source In-Memory Data Grid. Used for caching, messaging, clustering.
  • DistributedLog - DistributedLog (DL) is a high-performance, replicated log service, offering durability, replication and strong consistency as essentials for building reliable distributed systems.
  • Aeron - Efficient reliable unicast and multicast message transport.
  • Apache ActiveMQ - Message broker that implements JMS and converts synchronous to asynchronous communication.
  • Apache Camel - Glues together different transport APIs via Enterprise Integration Patterns.
  • Hermes - Fast and reliable message broker built on top of Kafka.
  • Nakadi - Provides a RESTful API on top of Kafka.
  • JeroMQ - Implementation of ZeroMQ.
  • Smack - Cross-platform XMPP client library.
  • HornetQ - An open source project to build a multi-protocol, embeddable, very high performance, clustered, asynchronous messaging system.
  • NSQ - NSQ is a realtime distributed messaging platform designed to operate at scale, handling billions of messages per day.
  • Beanstalkd - Beanstalk is a simple, fast work queue.

Distributed Databases

Databases in a distributed system that appear to applications as a single data source.

  • Apache Cassandra - Column-oriented and providing high availability with no single point of failure.
  • Apache HBase - Hadoop database for big data.
  • Druid - Real-time and historical OLAP data store that excel at aggregation and approximation queries.
  • Infinispan - Highly concurrent key/value datastore used for caching.
  • OpenTSDB - Scalable and distributed time series database written on top of Apache HBase.

Monitoring, testing, and managing tools for big data

  • Twitter Ambrose A platform for visualization and real-time monitoring of data workflows.
  • Umongo - Desktop app to browse and administer your MongoDB cluster.
  • Apache Ambari The Apache Ambari project is aimed at making Hadoop management simpler by developing software for provisioning, managing, and monitoring Apache Hadoop clusters. Ambari provides an intuitive, easy-to-use Hadoop management web UI backed by its RESTful APIs.
  • Apache Chukwa Chukwa is an open source data collection system for monitoring large distributed systems. Chukwa is built on top of the Hadoop Distributed File System (HDFS) and Map/Reduce framework and inherits Hadoop’s scalability and robustness. Chukwa also includes a flexible and powerful toolkit for displaying, monitoring and analyzing results to make the best use of the collected data.
  • Apache Bigtop Bigtop is an Apache Foundation project for Infrastructure Engineers and Data Scientists looking for comprehensive packaging, testing, and configuration of the leading open source big data components.
  • Apache BookKeeper BookKeeper is a replicated log service which can be used to build replicated state machines. A log contains a sequence of events which can be applied to a state machine. BookKeeper guarantees that each replica state machine will see all the same entries, in the same order.
  • Apache Crunch Provides a framework for writing, testing, and running MapReduce pipelines.
  • Apache MRUnit Apache MRUnit is a Java library that helps developers unit test Apache Hadoop map reduce jobs.
  • Apache Oozie Oozie is a workflow scheduler system to manage Apache Hadoop jobs.
  • Avaje Metrics - Collect Java/JVM application metrics to a file

Distribution

Tools which handle the distribution of applications

  • Bintray - Version control for binaries which handles the publishing. Can also be used with Maven or Gradle and has a free plan for open-source software or several business plans.
  • Boxfuse - Deployment of JVM application to AWS using the principles of Immutable Infrastructure.
  • Capsule - Simple and powerful packaging and deployment. A fat JAR on steroids or a "Docker for Java" that supports JVM-optimized containers.
  • Central Repository - Largest binary component repository available as a free service to the open-source community. Default used by Apache Maven and available in all other build tools.
  • IzPack - Setup authoring tool for cross-platform deployments.
  • JitPack - Easy to use package repository for GitHub. Builds Maven/Gradle projects on demand and publishes ready-to-use packages.
  • Nexus - Binary management with proxy and caching capabilities.
  • packr - Packs JARs, assets and the JVM for native distribution on Windows, Linux and Mac OS X.
  • Launch4j - Wraps JARs in lightweight and native Windows executables.

Document Processing

Libraries that assist with processing office document formats.

  • Apache POI - Supports OOXML (XLSX, DOCX, PPTX) as well as OLE2 (XLS, DOC or PPT).
  • documents4j - API for document format conversion using third-party converters such as MS Word.
  • docx4j - Creating and manipulating Microsoft Open XML files.

Throttling

Formal Verification

Formal-methods tools: proof assistants, model checking, symbolic execution etc.

  • CATG - Concolic unit testing engine. Automatically generates unit tests using formal methods.
  • Checker Framework - Pluggable type systems. Includes nullness types, physical units, immutability types and more.
  • Daikon - Daikon detects likely program invariants and can generate JML specs based on those invariats.
  • Java Path Finder (JPF) - JVM formal verification tool containing a model checker and more. Created by NASA.
  • JMLOK 2.0 - Detects nonconformances between code and JML specification through the feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected.
  • KeY - The KeY System is a formal software development tool that aims to integrate design, implementation, formal specification, and formal verification of object-oriented software as seamlessly as possible. Uses JML for specification and symbolic execution for verification.
  • OpenJML - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers.
  • TLA+ - A formal specification language developed by Leslie Lamport. It is used to design, model, document, and verify concurrent systems. TLA+ has been described as exhaustively-testable pseudocode and blueprints for software systems.

Functional Programming

Libraries that facilitate functional programming.

  • cyclops-react - Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.
  • derive4j - Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching, morphisms.
  • Fugue - Functional extensions to Guava.
  • Functional Java - Implements numerous basic and advanced programming abstractions that assist composition-oriented development.
  • Javaslang - Functional component library that provides persistent data types and functional control structures.
  • jOOλ - Extension to Java 8 which aims to fix gaps in lambda, providing numerous missing types and a rich set of sequential Stream API additions.

Game Development

Frameworks that support the development of games.

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

Geospatial

Libraries for working with geospatial data and algorithms.

  • Apache SIS - Library for developing geospatial applications.
  • Geo - GeoHash utilities in Java.
  • Geotoolkit.org - Library for developing geospatial applications. Built on top of the Apache SIS project.
  • GeoTools - Library that provides tools for geospatial data.
  • H2GIS - A spatial extension of the H2 database.
  • Jgeohash - Library that can assist Java developers in using the GeoHash algorithm.
  • Mapsforge - Software for the rendering of maps based on OpenStreetMap data.
  • Spatial4j - General purpose spatial/geospatial ASL licensed open-source Java library.

GUI

Libraries to create modern graphical user interfaces.

  • JavaFX - The successor of Swing.
  • Scene Builder - Visual layout tool for JavaFX applications.
  • SWT - The Standard Widget Toolkit (SWT) is a graphical widget toolkit for use with the Java platform.

Job Scheduling

  • Quartz - Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs; jobs whose tasks are defined as standard Java components that may execute virtually anything you may program them to do.

IDE

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

  • Eclipse - Established, open-souce project with support for lots of plugins and languages.
  • IntelliJ IDEA - Supports a lot of JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.
  • NetBeans - Provides integration for several Java SE and EE features from database access to HTML5.

Imagery

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

  • Imgscalr - Simple and efficient hardware-accelerated image-scaling library implemented in pure Java 2D.
  • Thumbnailator - Thumbnailator is a high-quality thumbnail generation library for Java.
  • TwelveMonkeys - Collection of plugins which extend the number of supported image file formats.
  • ZXing - Multi-format 1D/2D barcode image processing library.

JVM and JDK

Current implementations of the JVM/JDK.

  • Avian - JVM with both a JIT & AOT modes. Includes an iOS port.
  • JDK 9 - Early access releases of JDK 9.
  • OpenJDK - Open-source implementation for Linux.
  • ParparVM - VM with non-blocking concurrent GC for iOS.
  • Zulu OpenJDK 9 - Early access OpenJDK 9 builds for Windows, Linux, and Mac OS X.
  • Zulu OpenJDK - OpenJDK builds for Windows, Linux, and Mac OS X through Java 8.

Logging

Libraries that log the behavior of an application.

  • Apache Log4j 2 - Complete rewrite with a powerful plugin and configuration architecture.
  • graylog - Open-source aggregator suited for extended role and permission management.
  • kibana - Analyzes and visualizes log files. Some features require payment.
  • Logback - Robust logging library with interesting configuration options via Groovy.
  • logstash - Tool for managing log files.
  • SLF4J - Abstraction layer which is to be used with an implementation.
  • tinylog - Lightweight logging framework with static logger class.

Load Balancers

  • bamboo - Bamboo is a web daemon that automatically configures HAProxy for web services deployed on Apache Mesos and Marathon.
  • minuteman - A distributed, highly available service discovery & internal load balancer for distributed systems (microservices and containers).

Machine Learning

Tools that provide specific statistical algorithms which allow learning from data.

  • Apache Flink - Fast and reliable large-scale data processing engine.
  • Apache Mahout - Scalable algorithms focused on collaborative filtering, clustering and classification.
  • DeepDive - Creates structured information from unstructured data and integrates it into an existing database.
  • Deeplearning4j - Distributed and multi-threaded deep learning library.
  • H2O - Analytics engine for statistics over big data.
  • JSAT - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution.
  • Oryx 2 - A framework for building real-time large scale machine learning applications, which also includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
  • Smile - The Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.
  • Weka - Collection of algorithms for data mining tasks ranging from pre-processing to visualization.

Monitoring

Tools that monitor applications in production.

  • AppDynamics - Commercial performance monitor.
  • JavaMelody - Performance monitoring and profiling.
  • jmxtrans - Tool to connect to multiple JVMs and to query them for their attributes via JMX. Its query language is based on JSON, which allows non-Java programmers to access the JVMs attributes. Likewise, this tool supports different output writes, including Graphite, Ganglia, StatsD, among others.
  • Jolokia - JMX over REST.
  • Kamon - Tool for monitoring applications running on the JVM.
  • Metrics - Expose metrics via JMX or HTTP and can send them to a database.
  • New Relic - Commercial performance monitor.
  • Prometheus - Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.
  • SPM - Commercial performance monitor with distributing transaction tracing for JVM apps.
  • Takipi - Commercial in-production error monitoring and debugging.

Native

For working with platform-specific native libraries.

  • JNA - Work with native libraries without writing JNI. Also provides interfaces to common system libraries.
  • JNR - Work with native libraries without writing JNI. Also provides interfaces to common system libraries. Same goals as JNA, but faster, and serves as the basis for the upcoming Project Panama.

Natural Language Processing

Libraries that specialize on processing text.

  • CoreNLP - Stanford's CoreNLP provides a set of fundamental tools for tasks like tagging, named entity recognition, sentiment analysis and many more.
  • DKPro - A collection of re-usable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.
  • LingPipe - Toolkit for a variety of tasks ranging from POS tagging to sentiment analysis.
  • Apache OpenNLP - Toolkit for common tasks like tokenization.
  • JFlex - The Fast Scanner Generator for Java. JFlex is a lexical analyzer generator (also known as scanner generator).

Networking

Libraries for network programming.

  • Async Http Client - Asynchronous HTTP and WebSocket client library.
  • Comsat - Integrates standard Java web-related APIs with Quasar fibers and actors.
  • Finagle - Extensible RPC system used to construct high-concurrency servers. It implements uniform client and server APIs for several protocols, and is protocol agnostic, which simplifies the implementation of new protocols.
  • Grizzly - NIO framework. Used as a network layer in Glassfish.
  • Netty - Framework for building high performance network applications.
  • Nifty - Implementation of Thrift clients and servers on Netty.
  • OkHttp - HTTP+SPDY client.
  • Undertow - Web server providing both blocking and non-blocking API’s based on NIO. Used as a network layer in WildFly.
  • urnlib - Java library for representing, parsing and encoding URNs as in RFC 2141.

ORM

APIs which handle the persistence of objects.

  • Ebean - Provides simple and fast data access.
  • EclipseLink - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
  • Hibernate - Robust and widely used with an active community.
  • MyBatis - Couples objects with stored procedures or SQL statements.

PDF

Everything that helps with the creation of PDF files.

Benchmarking and Performance analysis

Tools for performance analysis, profiling and benchmarking.

  • jmh - Really good tool. Annotate methods for benchmarking. JMH is a Java harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targetting the JVM.
  • ab - Apache bench, while not strictly for Java, it's a great tool for load testing services.
  • honest-profiler - An low-overhead, bias-free sampling profiler.
  • jHiccup - Logs and records platform JVM stalls.
  • JProfiler - Commercial profiler.
  • LatencyUtils - Utilities for latency measurement and reporting.
  • XRebel - A commercial profiler for Java Web applications.
  • YourKit Java Profiler - Commercial profiler.

Reactive libraries

Libraries for developing reactive applications.

  • Reactive Streams - Provide a standard for asynchronous stream processing with non-blocking backpressure.
  • Reactor - Library for building reactive fast-data applications.
  • RxJava - Library for composing asynchronous and event-based programs using observable sequences from the JVM.
  • vert.x - Vert.x is event driven and non blocking. This means your app can handle a lot of concurrency using a small number of kernel threads. Vert.x lets your app scale with minimal hardware. Similar to node.js or Twisted for Python.

Java Service frameworks

  • Dropwizard - Dropwizard is a Java framework for developing ops-friendly, high-performance, RESTful web services. Dropwizard has out-of-the-box support for sophisticated configuration, application metrics, logging, operational tools, and much more.
  • gRPC - A high performance, open source, general RPC framework that puts mobile and HTTP/2 first.
  • Apache Thrift - The Apache Thrift software framework, for scalable cross-language services development, combines a software stack with a code generation engine to build services that work efficiently and seamlessly between C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Cocoa, JavaScript, Node.js, Smalltalk, OCaml and Delphi and other languages.
  • Apache CXF - CXF helps you build and develop services using frontend programming APIs, like JAX-WS and JAX-RS. These services can speak a variety of protocols such as SOAP, XML/HTTP, RESTful HTTP, or CORBA and work over a variety of transports such as HTTP, JMS or JBI.
  • Jersey - JAX-RS reference implementation.
  • Vert.x - Vert.x is event driven and non blocking. This means your app can handle a lot of concurrency using a small number of kernel threads. Vert.x lets your app scale with minimal hardware. Similar to node.js or Twisted for Python.
  • Microserver — A convenient extensible Microservices plugin system for Spring & Spring Boot, with over 30 plugins and growing, that supports both micro-monolith and pure microservices styles.

API Specification / Code generation from spec

  • Swagger (Open API) - The OpenAPI Specification (originally known as the Swagger Specification) is a specification for machine-readable interface files for describing, producing, consuming, and visualizing RESTful web services. A variety of tools can generate code, documentation and test cases given an interface file.
  • RAML - RESTful API Modeling Language (RAML) makes it easy to manage the whole API lifecycle from design to sharing.

REST Frameworks

  • Feign - HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket. Makes writing java http clients easier.
  • rest.li - Framework for building robust, scalable RESTful architectures using type-safe bindings and asynchronous, non-blocking IO with an end-to-end developer workflow that promotes clean practices, uniform interface design and consistent data modeling.
  • RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
  • RestExpress - Thin wrapper on the JBoss Netty HTTP stack to provide scaling and performance.
  • Restlet Framework - Pioneering framework with powerful routing and filtering capabilities, unified client and server API.
  • Retrofit - Type-safe REST client.

Math and Science

Libraries for math, scientific computing, analysis, and visualization.

  • axibase - BigDecimal implementation of Apache Commons Math Descriptive Statistics and Summary Statistics.
  • Apache Math - The Apache Commons Mathematics Library
  • DataMelt - Environment for scientific computation, data analysis and data visualization.
  • GraphStream - Library for modeling and analysis of dynamic graphs.
  • JGraphT - Graph library that provides mathematical graph-theory objects and algorithms.
  • JGraphX - Library for visualisation (mainly Swing) and interaction with node-edge graphs.
  • t-digest - A data structure for accurate on-line accumulation of rank-based statistics such as quantiles and trimmed means.

Retries, exponential backoff, failure handling

  • Failsafe - Simple, sophisticated failure handling.
  • async-retry - Asynchronous retrying for Java 7/8
  • guava-retrying - This is a small extension to Google's Guava library to allow for the creation of configurable retrying strategies for an arbitrary function call, such as something that talks to a remote service with flaky uptime.

Search

Engines which index documents for search and analysis.

  • Apache Lucene - High-performance, full-featured cross-platform text search engine library.
  • Apache Solr - 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.

Security

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

  • Apache Shiro - Performs authentication, authorization, cryptography and session management.
  • Bouncy Castle - All-purpose cryptographic library. JCA provider, wide range of functions from basic helpers to PGP/SMIME operations.
  • Cryptomator - Multiplatform transparent client-side encryption of files in the cloud.
  • Google Keyczar - Easy to use, yet safe encryption framework with key versioning.
  • Keycloak - Integrated SSO and IDM for browser apps and RESTful web services.
  • OACC - Provides permission-based authorization services.
  • pac4j - Easy and powerful Java security engine to authenticate users, get their profiles, and manage authorizations in order to secure a Java web application.
  • PicketLink - Umbrella project for security and identity management.

Serialization

Libraries that handle serialization with high efficiency.

  • FlatBuffers - Memory efficient serialization library that can access serialized data without unpacking and parsing it.
  • FST - JDK compatible high performance object graph serialization.
  • Kryo - Fast and efficient object graph serialization framework.
  • MessagePack - Efficient binary serialization format.

Server

Servers which are specifically used to deploy applications.

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

Template Engine

Tools which substitute expressions in a template.

  • handlebars.java - Logic-less and semantic Mustache templates.
  • Mustache.java - Implementation of mustache.js (web application templating system) for Java.
  • Thymeleaf - Aims to be a substitute for JSP and works for XML files in general.
  • Apache Velocity - Templates for HTML pages, emails or source code generation in general.
  • FreeMarker - General templating engine without any heavyweight or opinionated dependencies.

Testing

Tools that test from model to the view.

  • JUnit - Common testing framework.
  • TestNG - Testing framework.
  • ConcurrentUnit - Toolkit for testing multi-threaded and asynchronous applications.
  • Hamcrest - Matchers that can be combined to create flexible expressions of intent.
  • Apache JMeter - Functional testing and performance measurements.
  • Arquillian - Integration and functional testing platform for Java EE containers.
  • AssertJ - Fluent assertions that improve readability.
  • Awaitility - DSL for synchronizing asynchronous operations.
  • Citrus - Integration testing framework with focus on client- and serverside messaging.
  • Cucumber - BDD testing framework.
  • Gatling - Load testing tool designed for ease of use, maintainability and high performance.
  • GreenMail - In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL.
  • J8Spec - J8Spec is a library that allows tests written in Java to follow the BDD style introduced by RSpec and Jasmine.
  • JGiven - Developer-friendly BDD testing framework compatible with JUnit and TestNG.
  • JMockit - Mocks static, final methods and more.
  • junit-dataprovider - A TestNG like dataprovider runner for JUnit.
  • JUnitParams - Creation of readable and maintainable parametrised tests.
  • Mockito - Creation of test double objects in automated unit tests for the purpose of TDD or BDD.
  • Moco - Concise web services for stubs and mocks, Duke's Choice Award 2013.
  • PIT - Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test-suites.
  • PowerMock - Enables mocking of static methods, constructors, final classes and methods, private methods and removal of static initializers.
  • REST Assured - Java DSL for easy testing for REST/HTTP services.
  • Selenide - Concise API around Selenium to write stable and readable UI tests.
  • Selenium - Portable software testing framework for web applications.
  • Spock - JUnit-compatible framework featuring an expressive Groovy-derived specification language.
  • Truth - Google's assertion and proposition framework.
  • WireMock - Stubbs and mocks web services.
  • Betamax - Betamax is a tool for mocking external HTTP resources such as web services and REST APIs in your tests. The project was inspired by the VCR library for Ruby.

Utility

Libraries which provide general utility functions.

  • Apache Commons - Provides different general purpose functions like configuration, validation, collections, file upload or XML processing.
  • CRaSH - Provides a shell into a JVM that's running CRaSH. Used by Spring Boot and others.
  • Dex - Java/JavaFX tool capable of powerful ETL and data visualization.
  • Gephi - Cross-platform for visualizing and manipulating large graph networks.
  • Guava - Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and so forth.
  • JADE - Framework and environment for building and to debugging multi-agent systems.
  • JavaVerbalExpressions - A library that helps to construct difficult regular expressions.
  • Protégé - Provides an ontology editor and a framework to build knowledge-based systems.

Web Crawling

Libraries that analyze the content of websites.

  • Apache Nutch - Highly extensible, highly scalable web crawler for production environment.
  • Crawler4j - Simple and lightweight web crawler.
  • JSoup - Scrapes, parses, manipulates and cleans HTML.

Web Frameworks

  • Rapidoid - A simple, secure and extremely fast framework consisting of embedded HTTP server, GUI components and dependency injection.
  • Play Framework - Uses convention over configuration, hot code reloading and display of errors in the browser.
  • Activeweb - Fully featured Java web framework inspired by Ruby on Rails, and provides such features as on the fly code compilation, full test framework, beautiful restful routes, based on Servlet API, plays nice with other Java standards, and uses ActiveJDBC ORM as DB access layer.
  • BootsFaces - Takes the best from Bootstrap 3 and jQuery UI to let you develop Front-end Enterprise Applications fast and easy
  • JavaServer Faces - Oracle's open-source implementation of the JSF standard, Mojarra.
  • JavaServer Pages - Common templating for websites with custom tag libraries.
  • GWT - 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.
  • Apache Tapestry - Component-oriented framework for creating dynamic, robust, highly scalable web applications.
  • Apache Wicket - Component-based web application framework similar to Tapestry with a stateful GUI.
  • Blade - Lightweight, modular framework which aims to be elegant and simple.
  • Grails - Groovy framework with the aim to provide a highly productive environment by favoring convention over configuration, no XML and support for mixins.
  • Jooby - Scalable, fast and modular micro framework which offers multiple programming models.
  • Ninja - Full stack web framework.
  • Pippo - Small, highly modularized Sinatra-like framework.
  • PrimeFaces - JSF framework which has a free and a commercial version with support. Provides several frontend components.
  • Ratpack - Set of libraries that facilitate fast, efficient, evolvable and well tested HTTP applications.
  • 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.
  • Spark - Sinatra inspired framework. A micro framework for creating web applications in Java 8 with minimal effort.

Web development libraries

Model Mapping

Frameworks that ease bean mapping.

  • Dozer - Mapper that copies data from one object to another, using annotations, API or XML configuration. JMapper - Using byte code manipulation for lightning fast mapping. Supporting annotations, API or XML configuration.
  • MapStruct - Code generator which simplifies mappings between different bean types, based on a convention over configuration approach.
  • ModelMapper - ModelMapper is an intelligent object mapping library that automatically maps objects to each other.
  • Orika - Orika is a Java Bean mapping framework that recursively copies (among other capabilities) data from one object to another.
  • Selma - Stupid Simple Statically Linked Mapper. Selma is an Annotation Processor Based bean mapper.

Workflows

  • Airflow - A workflow management platform by Airbnb.

Miscellaneous

Everything else.

  • Codename One - Cross platform solution for writing native mobile (iOS, Android, etc.)
  • Design Patterns - Implementation and explanation of the most common design patterns.
  • J2ObjC - Java to Objective-C translator for porting Android libraries to iOS.
  • JBake - Java based static site/blog generator.
  • jabba - Java Version Manager inspired by nvm.
  • Jimfs - In-memory file system by Google.
  • JPad - Snippet runner.
  • Lanterna - Easy console text GUI library similar to curses.
  • LightAdmin - Pluggable CRUD UI library for rapid application development.
  • Modern Java - A Guide to Java 8 - Popular Java 8 guide.
  • OpenRefine - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
  • Spring - Provides many packages ranging from dependency injection to aspect-oriented programming to security.
  • Java Modeling Language (JML) - Behavioral interface specification language that can be used to specify the behavior of code modules. It combines the design by contract approach of Eiffel and the model-based specification approach of the Larch family of interface specification languages, with some elements of the refinement calculus. Used by several other verification tools.
  • Monod - Monod is a (relatively) secure and offline-first Markdown editor we built at TailorDev in order to learn React.js.
  • prismjs - A Javascript syntax highlighting library.

Resources

Communities

Active discussions.

  • r/java - Subreddit for the Java community.
  • stackoverflow - Question/answer platform.
  • vJUG - Virtual Java User Group.

Influential Books

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

Subpages

Sources