awesome-java

A curated list of awesome frameworks, libraries and software for the Java programming language.
https://github.com/eric-erki/awesome-java

Last synced: about 12 hours ago
JSON representation

Projects
- Bean Mapping
  - dOOv - Provides fluent API for typesafe domain model validation and mapping. It uses annotations, code generation and a type safe DSL to make bean validation and mapping fast and easy.
  - Dozer - Mapper that copies data from one object to another using annotations and API or XML configuration.
  - JMapper - Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.
  - MapStruct - Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.
  - ModelMapper - Intelligent object mapping library that automatically maps objects to each other.
  - Orika - JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.
  - reMap - Lambda and method handle-based mapping which requires code and not annotations if objects have different names.
  - Selma - Annotation processor-based bean mapper.
  - dOOv - Provides fluent API for typesafe domain model validation and mapping. It uses annotations, code generation and a type safe DSL to make bean validation and mapping fast and easy.
  - Selma - Annotation processor-based bean mapper.
- Build
  - Buck - Encourages the creation of small, reusable modules consisting of code and resources.
  - Gradle - Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven's dependency management.
  - Bazel - Tool from Google that builds code quickly and reliably.
- Bytecode Manipulation
  - bytecode-viewer - Java 8 Jar & Android APK reverse engineering suite. (GPL-3.0-only)
  - cglib - Bytecode generation library.
  - Javassist - Tries to simplify bytecode editing.
  - Mixin - Manipulate bytecode at runtime using real Java code.
  - Perses - Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.
  - ASM - All-purpose, low-level bytecode manipulation and analysis.
  - Perses - Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.
- Caching
  - Caffeine - High-performance, near-optimal caching library.
  - Ehcache - Distributed general-purpose cache.
- CLI
  - ASCII Table - Library to draw tables in ASCII.
  - Airline - Annotation-based framework for parsing Git-like command-line arguments.
  - args4j - Small library to parse command-line arguments.
  - Jansi - ANSI escape codes to format console output.
  - Java ASCII Render - Graphical primitives for the console.
  - JCommander - Command-line argument-parsing framework with custom types and validation via implementing interfaces.
  - args4j - Small library to parse command-line arguments.
  - JLine - Includes features from modern shells like completion or history.
  - JOpt Simple - Fluent parser that uses the POSIX#getopt and GNU#getopt_long syntaxes.
  - Text-IO - Aids the creation of full console-based applications.
  - Lanterna - Easy console text-GUI library, similar to curses. (LGPL-3.0-only)
  - jbock - Typesafe, reflection-free, annotation based command-line parser.
  - Jexer - Advanced console (and Swing) text user interface (TUI) library, with mouse-draggable windows, built-in terminal window manager, and sixel image support. Looks like [Turbo Vision](https://en.wikipedia.org/wiki/Turbo_Vision).
- Cluster Management
  - Singularity - Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.
  - Apache Aurora - Mesos framework for long-running services and cron jobs.
  - Apache Mesos - Abstracts CPU, memory, storage, and other compute resources away from machines.
  - Singularity - Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.
- Code Analysis
  - NullAway - Eliminates NullPointerExceptions with low build-time overhead.
  - PMD - Source code analysis for finding bad coding practices.
  - Infer - Modern static analysis tool for verifying the correctness of code.
  - Checkstyle - Static analysis of coding conventions and standards. (LGPL-2.1-or-later)
  - Error Prone - Catches common programming mistakes as compile-time errors.
  - SonarJava - Static analyzer for SonarQube & SonarLint. (LGPL-3.0-only)
  - Spoon - Library for analyzing and transforming Java source code.
  - Spotbugs - Static analysis of bytecode to find potential bugs. (LGPL-2.1-only)
  - Sourcetrail - Visual source code navigator.
- Configuration
  - KAConf - Annotation-based configuration system for Java and Kotlin.
  - owner - Reduces boilerplate of properties.
  - owner - Reduces boilerplate of properties.
  - centraldogma - Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.
  - cfg4j - Modern configuration library for distributed apps written in Java.
  - config - Configuration library for JVM languages.
  - dotenv - Twelve-factor configuration library which uses environment-specific files.
- CSV
  - uniVocity-parsers - One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.
  - jackson-dataformat-csv - Jackson extension for reading and writing CSV.
  - Super CSV - Powerful CSV parser with support for Dozer, Joda-Time and Java 8.
  - opencsv - Simple CSV parser.
- Data Structures
  - Big Queue - Fast and persistent queue based on memory-mapped files.
  - HyperMinHash-java - Probabilistic data structure for computing union, intersection, and set cardinality in loglog space.
  - Persistent Collection - Persistent and immutable analogue of the Java Collections Framework.
  - Protobuf - Google's data interchange format.
  - Tape - Lightning-fast, transactional, file-based FIFO.
  - Wire - Clean, lightweight protocol buffers.
  - Apache Avro - Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.
  - Apache Orc - Fast and efficient columnar storage format for Hadoop-based workloads.
- Database
  - eXist - NoSQL document database and application platform. (LGPL-2.1-only)
  - FlexyPool - Brings metrics and failover strategies to the most common connection pooling solutions.
  - Flyway - Simple database migration tool.
  - HikariCP - High-performance JDBC connection pool.
  - jasync-sql - Async DB driver for MySQL and PostgreSQL.
  - JDBI - Convenient abstraction of JDBC.
  - Jest - Client for the Elasticsearch REST API.
  - Realm - Mobile database to run directly inside phones, tablets or wearables.
  - requery - Modern, lightweight but powerful object mapping and SQL generator. Easily map to or create databases, or perform queries and updates from any Java-using platform.
  - Xodus - Highly concurrent transactional schema-less and ACID-compliant embedded database.
  - Liquibase - Database-independent library for tracking, managing and applying database schema changes.
  - Presto - Distributed SQL query engine for big data.
  - Jedis - Small client for interaction with Redis, with methods for commands.
  - AranoDB - ArangoDB Java driver.
  - Chronicle Map - Efficient, in-memory (opt. persisted to disk), off-heap key-value store.
  - jetcd - Client library for etcd.
  - Jinq - Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ).
  - Leaf - Distributed ID generate service.
  - MariaDB4j - Launcher for MariaDB that requires no installation or external dependencies.
  - Querydsl - Typesafe unified queries.
  - Redisson - Allows for distributed and scalable data structures on top of a Redis server.
  - Speedment - Database access library that utilizes Java 8's Stream API for querying.
  - Apache Phoenix - High-performance relational database layer over HBase for low-latency applications.
  - druid - High-performance, column-oriented, distributed data store.
  - sql2o - Thin JDBC wrapper that simplifies database access and provides simple mapping of ResultSets to POJOs.
- Dependency Injection
  - Feather - Ultra-lightweight, JSR-330-compliant dependency injection library.
  - Inversion of Control
  - Dagger - Compile-time injection framework without reflection.
  - Governator - Extensions and utilities that enhance Google Guice.
  - Guice - Lightweight and opinionated framework that completes Dagger.
  - HK2 - Lightweight and dynamic dependency injection framework.
  - JayWire - Lightweight dependency injection framework. (LGPL-3.0-only)
  - Apache DeltaSpike - CDI extension framework.
- Distributed Applications
  - JGroups - Toolkit for reliable messaging and cluster creation.
  - Orbit - Virtual actors; adds another level of abstraction to traditional actors.
  - Quasar - Lightweight threads and actors for the JVM.
  - Atomix - Fault-tolerant distributed coordination framework.
  - Failsafe - Simple failure handling with retries and circuit breakers.
  - JGroups - Toolkit for reliable messaging and cluster creation.
  - Dropwizard Circuit Breaker - Circuit breaker design pattern for Dropwizard. (GPL-2.0-only)
  - resilience4j - Functional fault tolerance library.
  - ScaleCube Services - Embeddable Cluster-Membership library based on SWIM and gossip protocol.
  - Zuul - Gateway service that provides dynamic routing, monitoring, resiliency, security, and more.
  - Hazelcast - Highly scalable in-memory datagrid with a free open-source version.
  - Orbit - Virtual actors; adds another level of abstraction to traditional actors.
- Distributed Transactions
  - Bitronix - Simple but complete implementation of the JTA 1.1 API.
  - Seata - Delivers high performance and easy to use distributed transaction services under a microservices architecture.
  - Seata - Delivers high performance and easy to use distributed transaction services under a microservices architecture.
- Distribution
  - Capsule - Simple and powerful packaging and deployment. A fat JAR on steroids, or a "Docker for Java" that supports JVM-optimized containers.
  - packr - Packs JARs, assets and the JVM for native distribution on Windows, Linux and macOS.
  - really-executable-jars-maven-plugin - Maven plugin for making self-executing JARs.
  - IzPack - Setup authoring tool for cross-platform deployments.
  - Boxfuse ![c - Deployment of JVM applications to AWS using the principles of immutable infrastructure.
  - 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.
  - jlink.online - Builds optimized runtimes over HTTP.
- Document Processing
  - zerocell - Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead.
  - documents4j - API for document format conversion using third-party converters such as MS Word.
  - docx4j - Create and manipulate Microsoft Open XML files.
- Financial
  - Parity - Platform for trading venues.
  - Philadelphia - Low-latency financial information exchange.
  - Square - Integration with the Square API.
  - Stripe - Integration with the Stripe API.
- Formal Verification
  - CATG - Concolic unit testing engine. Automatically generates unit tests using formal methods.
  - Java Path Finder (JPF) - JVM formal verification tool containing a model checker and more. Created by NASA.
  - OpenJML - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)
  - Daikon - Detects likely program invariants and generates JML specs based on those invariants.
  - JMLOK 2.0 - Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected. (GPL-3.0-only)
  - Checker Framework - Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)
- Functional Programming
  - derive4j - Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms. (GPL-3.0-only)
  - Fugue - Functional extensions to Guava.
  - jOOλ - Extension to Java 8 that aims to fix gaps in lambda by providing numerous missing types and a rich set of sequential Stream API additions.
  - protonpack - Collection of stream utilities.
  - StreamEx - Enhances Java 8 Streams.
  - Functional Java - Implements numerous basic and advanced programming abstractions that assist composition-oriented development.
  - cyclops-react - Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.
  - Vavr - Functional component library that provides persistent data types and functional control structures.
- Game Development
  - FXGL - JavaFX Game Development Framework.
  - libGDX - All-round cross-platform, high-level framework.
  - FXGL - JavaFX Game Development Framework.
  - jMonkeyEngine - Game engine for modern 3D development.
  - LWJGL - Robust framework that abstracts libraries like OpenGL/CL/AL.
- Geospatial
  - Geo - GeoHash utilities in Java.
  - Geotoolkit.org - Library for developing geospatial applications. Built on top of the Apache SIS project. (LGPL-2.1-only)
  - GraphHopper - Road-routing engine. Used as a Java library or standalone web service.
  - H2GIS - Spatial extension of the H2 database. (LGPL-3.0-only)
  - Jgeohash - Library for using the GeoHash algorithm.
  - Mapsforge - Map rendering based on OpenStreetMap data. (LGPL-3.0-only)
  - Spatial4j - General-purpose spatial/geospatial library.
  - H2GIS - Spatial extension of the H2 database. (LGPL-3.0-only)
  - Geotoolkit.org - Library for developing geospatial applications. Built on top of the Apache SIS project. (LGPL-2.1-only)
  - Jgeohash - Library for using the GeoHash algorithm.
- High Performance
  - Disruptor - Inter-thread messaging library.
  - JCTools - Concurrency tools currently missing from the JDK.
  - HPPC - Primitive collections.
  - Koloboke - Hash sets and hash maps.
  - Agrona - Data structures and utility methods that are common in high-performance applications.
  - Eclipse Collections - Collections framework inspired by Smalltalk.
  - fastutil - Fast and compact type-specific collections.
  - Disruptor - Inter-thread messaging library.
- Hypermedia Types
  - Siren4J - Library for the Siren specification.
  - JSON-LD - JSON-LD implementation.
  - Siren4J - Library for the Siren specification.
- HTTP Clients
  - Async Http Client - Asynchronous HTTP and WebSocket client library.
  - Feign - HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.
  - Play WS - Typesafe client with reactive streams and caching.
  - Ribbon - Client-side IPC library that is battle-tested in cloud.
  - Riptide - Client-side response routing for Spring's RestTemplate.
  - unirest-java - Simplified, lightweight HTTP client library.
  - Feign - HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.
  - restQL-core-java - Microservice query language that fetches information from multiple services.
  - OkHttp - HTTP and SPDY client.
  - Retrofit - Typesafe REST client.
- Imagery
  - Tess4J - JNA wrapper for Tesseract OCR API.
  - Thumbnailator - High-quality thumbnail generation library.
  - TwelveMonkeys - Collection of plugins that extend the number of supported image file formats.
  - image-comparison - Compares two images with the same sizes and shows the differences visually by drawing rectangles.
  - ZXing - Multi-format 1D/2D barcode image processing library.
  - Imgscalr - Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.
- Introspection
  - ClassGraph - ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.
  - Mirror - Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.
  - ReflectASM - ReflectASM is a very small Java library that provides high performance reflection by using code generation.
  - Reflections - Reflections scans your classpath, indexes the metadata, allows you to query it on runtime and may save and collect that information for many modules within your project.
  - jOOR - jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package.
  - Mirror - Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.
- Job Scheduling
  - Quartz - Feature-rich, open source job scheduling library that can be integrated within virtually any Java application.
  - Sundial - Lightweight framework to simply define jobs, define triggers and start the scheduler.
  - Wisp - Simple library with minimal footprint and straightforward API.
  - db-scheduler - Persistent and cluster-friendly scheduler.
- JSON
  - DSL-JSON - JSON library with advanced compile time databinding.
  - HikariJSON - High-performance JSON parser, 2x faster than Jackson.
  - jackson-modules-java8 - Set of Jackson modules for Java 8 datatypes and features.
  - jsoniter - Fast and flexible library with iterator and lazy parsing API.
  - Yasson - Binding layer between classes and JSON documents similar to JAXB.
  - JsonSurfer - Streaming JsonPath processor dedicated to processing big and complicated JSON data.
  - Gson - Serializes objects to JSON and vice versa. Good performance with on-the-fly usage.
  - Jackson - Similar to GSON, but offers performance gains if you need to instantiate the library more often.
  - Moshi - Modern JSON library, less opinionated and uses built-in types like List and Map.
  - Genson - Powerful and easy-to-use Java-to-JSON conversion library.
  - JsonSurfer - Streaming JsonPath processor dedicated to processing big and complicated JSON data.
  - JsonPath - Extract data from JSON using XPATH-like syntax.
  - Jackson-datatype-money - Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types.
  - 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. Outperforms GSON & Jackson's library.
  - fastjson - Very fast processor with no additional dependencies and full data binding.
  - Jolt - JSON to JSON transformation tool.
  - Genson - Powerful and easy-to-use Java-to-JSON conversion library.
  - Yasson - Binding layer between classes and JSON documents similar to JAXB.
- JVM and JDK
  - OpenJ9 - High performance, enterprise-calibre, flexibly licensed, openly-governed cross-platform JVM extending and augmenting the runtime technology components from the Eclipse OMR and OpenJDK project.
  - SAP Machine - SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)
  - Liberica JDK - Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)
  - Open JDK - Open JDK community home. (GPL-2.0-only WITH Classpath-exception-2.0)
  - OpenJ9 - High performance, enterprise-calibre, flexibly licensed, openly-governed cross-platform JVM extending and augmenting the runtime technology components from the Eclipse OMR and OpenJDK project.
  - Avian - JVM with JIT, AOT modes and iOS port.
  - Graal - Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)
  - ParparVM - VM with non-blocking, concurrent GC for iOS. (GPL-2.0-only WITH Classpath-exception-2.0)
  - RedHat Open JDK - RedHat's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)
  - Adopt Open JDK - Community-driven OpenJDK builds, including both HotSpot and OpenJ9.
  - Corretto - No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)
  - Liberica JDK - Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)
  - SAP Machine - SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)
  - Zulu - OpenJDK builds for Windows, Linux, and macOS. (GPL-2.0-only WITH Classpath-exception-2.0)
- Logging
  - Logbook - Extensible, open-source library for HTTP request and response logging.
  - Tracer - Call tracing and log correlation in distributed systems.
  - Kibana - Analyzes and visualizes log files. Some features require payment.
  - Logstash - Tool for managing log files.
  - p6spy - Enables logging for all JDBC transactions without changes to the code.
  - Apache Log4j 2 - Complete rewrite with a powerful plugin and configuration architecture.
  - Logback - Robust logging library with interesting configuration options via Groovy.
  - tinylog - Lightweight logging framework with static logger class.
  - Tracer - Call tracing and log correlation in distributed systems.
- Machine Learning
  - DatumBox - Provides several algorithms and pre-trained models for natural language processing.
  - DeepDive - Creates structured information from unstructured data and integrates it into an existing database.
  - Synapses - Lightweight library for neural networks.
  - DeepDive - Creates structured information from unstructured data and integrates it into an existing database.
  - Deeplearning4j - Distributed and multi-threaded deep learning library.
  - JSAT - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)
  - Oryx 2 - Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
  - Smile - Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.
  - Apache Flink - Fast, reliable, large-scale data processing engine.
  - Weka - Collection of algorithms for data mining tasks ranging from pre-processing to visualization. (GPL-3.0-only)
- Messaging
  - NATS client - NATS client.
  - Aeron - Efficient, reliable, unicast and multicast message transport.
  - EventBus - Simple publish/subscribe event bus.
  - JeroMQ - Implementation of ZeroMQ.
  - Nakadi - Provides a RESTful API on top of Kafka.
  - RabbitMQ Java client - RabbitMQ client.
  - Smack - Cross-platform XMPP client library.
  - Apache ActiveMQ - Message broker that implements JMS and converts synchronous to asynchronous communication.
  - Apache Camel - Glues together different transport APIs via Enterprise Integration Patterns.
  - Apache Kafka - High-throughput distributed messaging system.
  - Hermes - Fast and reliable message broker built on top of Kafka.
  - NATS client - NATS client.
- Microservice
  - Apollo - Libraries for writing composable microservices.
  - Armeria - Asynchronous RPC/REST client/server library built on top of Java 8, Netty, HTTP/2, Thrift and gRPC.
  - consul-api - Client for the Consul API: a distributed, highly available and datacenter-aware registry/discovery service.
  - Eureka - REST-based service registry for resilient load balancing and failover.
  - Apollo - Libraries for writing composable microservices.
  - Micronaut - Modern full-stack framework with focus on modularity, minimal memory footprint and startup time.
- Miscellaneous
  - FF4J - Feature Flags for Java.
  - FizzBuzz Enterprise Edition - No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)
  - J2ObjC - Java-to-Objective-C translator for porting Android libraries to iOS.
  - JavaCV - Java interface to OpenCV, FFmpeg, and more.
  - JBot - Framework for building chatbots. (GPL-3.0-only)
  - JCuda - JCuda offers Java bindings for CUDA and CUDA-related libraries.
  - Jimfs - In-memory file system.
  - Maven Wrapper - Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.
  - Membrane Service Proxy - Open-source, reverse-proxy framework.
  - MinimalFTP - Lightweight, small and customizable FTP server.
  - Modernizer - Detect uses of legacy Java APIs.
  - PipelinR - Small utility library for using handlers and commands with pipelines.
  - Polyglot for Maven - Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.
  - Simple Java Mail - Mailing with a clean and fluent API.
  - Smooks - Extensible framework for building applications that process data which means bindings, transformations, message processing and enrichment. (LGPL-3.0-only)
  - TypeTools - Tools for resolving generic types.
  - XMLBeam - Processes XML by using annotations or XPath within code.
  - yGuard - Obfuscation via renaming and shrinking.
  - JavaX - Reinventing and extending Java with a focus on simplicity. (No explicit license)
  - Membrane Service Proxy - Open-source, reverse-proxy framework.
  - JavaX - Reinventing and extending Java with a focus on simplicity. (No explicit license)
  - JCuda - JCuda offers Java bindings for CUDA and CUDA-related libraries.
  - JPad - Snippet runner.
  - OctoLinker - Browser extension which allows to navigate through code on GitHub more efficiently.
  - CQEngine - Ultra-fast, SQL-like queries on Java collections.
  - Design Patterns - Implementation and explanation of the most common design patterns.
  - Modern Java - A Guide to Java 8 - Popular Java 8 guide.
  - JPad - Snippet runner.
  - JBake - Static website generator.
  - JBot - Framework for building chatbots. (GPL-3.0-only)
  - Joda-Money - Basic currency and money classes and algorithms not provided by the JDK.
  - Modernizer - Detect uses of legacy Java APIs.
- Monitoring
  - Automon - Combines the power of AOP with monitoring and/or logging tools.
  - Failsafe Actuator - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
  - LeakCanary - Memory leak detection.
  - Failsafe Actuator - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
  - JavaMelody - Performance monitoring and profiling.
  - Jaeger client - Jaeger client.
  - jmxtrans - Connect to multiple JVMs and query them for their attributes via JMX. Its query language is based on JSON, which allows non-Java programmers to access the JVM attributes. Supports different output writes, including Graphite, Ganglia, and StatsD.
  - nudge4j - Remote developer console from the browser for Java 8 via bytecode injection.
  - SPM ![c - Performance monitor with distributing transaction tracing for JVM apps.
  - Stagemonitor - Open-source performance monitoring and transaction tracing for JVM apps.
  - Sysmon - Lightweight platform monitoring tool for Java VMs.
  - Pinpoint - Open-source APM tool.
  - inspectIT - Captures detailed run-time information via hooks that can be changed on the fly. It supports tracing over multiple systems via the OpenTracing API and can correlate the data with end user monitoring.
  - Kamon ![c - Tool for monitoring applications running on the JVM.
  - Metrics - Expose metrics via JMX or HTTP and send them to a database.
- Testing
  - Truth - Google's fluent assertion and proposition framework.
  - MockServer - Allows mocking of systems integrated with HTTPS.
  - GreenMail - In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL. (GPL-2.0-only)
  - JBehave - Extensively configurable framework that describes stories.
  - Hamcrest - Matchers that can be combined to create flexible expressions of intent.
  - pojo-tester - Automatically performs tests on basic POJO methods. (LGPL-3.0-only)
  - Pact JVM - Consumer-driven contract testing.
  - Awaitility - DSL for synchronizing asynchronous operations.
  - PowerMock - Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.
  - ConcurrentUnit - Toolkit for testing multi-threaded and asynchronous applications.
  - Hoverfly Java - Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services.
  - Karate - DSL that combine API test-automation, mocks and performance-testing making testing REST/HTTP services easy.
  - Cucumber - Provides a way to describe features in a plain language which customers can understand.
  - J8Spec - Follows a Jasmine-like syntax.
  - Lamdba Behave - Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.
  - Beanmother - Sets up beans from YAML fixtures.
  - Fixture Factory - Generates fake objects from a template.
  - jFairy - Fake data generator.
  - Randomized Testing - JUnit test runner and plugins for running JUnit tests with pseudo-randomness.
  - Java Faker - Port of Ruby's fake data generator.
  - ArchUnit - Test library for specifying and asserting architecture rules.
  - XMLUnit - Simplifies testing for XML output.
  - junit-dataprovider - TestNG-like data provider/runner for JUnit.
  - Mutability Detector - Reports whether instances of a given class are immutable.
  - raml-tester - Tests if a request/response matches a given RAML definition.
  - TestContainers - Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.
  - JMockit - Integration testing, API mocking and faking, and code coverage.
  - Mockito - Mocking framework that lets you write tests with a clean and simple API.
  - Moco - Concise web services for stubs and mocks.
  - Serenity BDD - Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.
  - REST Assured - DSL for easy testing of REST/HTTP services.
  - Cukes-REST - Collection of Gherkin steps for REST-service testing using Cucumber.
  - JGiven - Provides a fluent API which allows for simpler composition.
  - Apache JMeter - Functional testing and performance measurements.
  - Arquillian - Integration and functional testing platform for Java EE containers.
  - Citrus - Integration testing framework that focuses on both client- and server-side messaging.
  - Gatling - Load testing tool designed for ease of use, maintainability and high performance.
  - JUnit - Common testing framework.
  - jqwik - Engine for property-based testing built on JUnit 5.
  - PIT - Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.
  - AssertJ - Fluent assertions that improve readability.
  - JSONAssert - Simplifies testing JSON strings.
  - WireMock - Stubs and mocks web services.
- Utility
  - Protégé - Provides an ontology editor and a framework to build knowledge-based systems.
  - Guava - Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.
  - cactoos - Collection of object-oriented primitives.
  - bucket4j - Rate limiting library based on token-bucket algorithm.
  - CRaSH - Provides a shell into a JVM that's running CRaSH. Used by Spring Boot and others. (LGPL-2.1-or-later)
  - Dex - Java/JavaFX tool capable of powerful ETL and data visualization.
  - fswatch - Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.
  - Gephi - Cross-platform for visualizing and manipulating large graph networks. (GPL-3.0-only)
  - JavaVerbalExpressions - Library that helps with constructing difficult regular expressions.
  - JGit - Lightweight, pure Java library implementing the Git version control system.
  - minio-java - Provides simple APIs to access any Amazon S3-compatible object storage server.
  - Underscore-java - Port of Underscore.js functions.
  - JADE - Framework and environment for building and debugging multi-agent systems. (LGPL-2.0-only)
- Web Crawling
  - Apache Nutch - Highly extensible, highly scalable web crawler for production environments.
  - Crawler4j - Simple and lightweight web crawler.
  - StormCrawler - SDK for building low-latency and scalable web crawlers.
  - webmagic - Scalable crawler with downloading, url management, content extraction and persistent.
  - StormCrawler - SDK for building low-latency and scalable web crawlers.
  - jsoup - Scrapes, parses, manipulates and cleans HTML.
- Web Frameworks
  - 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.
  - Bootique - Minimally opinionated framework for runnable apps.
  - Vaadin Flow - Event-driven framework that uses standard web components. Server-side architecture with Ajax on the client side.
  - Firefly - Asynchronous framework for rapid development of high-performance web application.
  - Pippo - Small, highly modularized, Sinatra-like framework.
  - Takes - Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.
  - Blade - Lightweight, modular framework that aims to be elegant and simple.
  - Grails - Groovy framework that provides a highly productive environment by favoring convention over configuration, no XML and support for mixins.
  - Jooby - Scalable, fast and modular micro-framework that offers multiple programming models.
  - Ninja - Full-stack web framework.
  - Play - Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.
  - Ratpack - Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications.
- PDF
  - Dynamic Jasper - Abstraction layer to JasperReports. (LGPL-3.0-only)
  - DynamicReports - Simplifies JasperReports. (LGPL-3.0-only)
  - flyingsaucer - XML/XHTML and CSS 2.1 renderer. (LGPL-2.1-or-later)
  - JasperReports - Complex reporting engine. (LGPL-3.0-only)
  - Open HTML to PDF - Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.
  - OpenPDF - Open-source iText fork. (LGPL-3.0-only & MPL-2.0)
  - iText ![c - Creates PDF files programmatically.
  - Apache FOP - Creates PDFs from XSL-FO.
  - Apache PDFBox - Toolbox for creating and manipulating PDFs.
  - Dynamic Jasper - Abstraction layer to JasperReports. (LGPL-3.0-only)
- Code Coverage
  - Clover - Relies on source-code instrumentation instead of bytecode instrumentation.
  - JaCoCo - Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.
  - Cobertura - Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)
- Code Generators
  - Joda-Beans - Small framework that adds queryable properties to Java, enhancing JavaBeans.
  - ADT4J - JSR-269 code generator for algebraic data types.
  - Auto - Generates factory, service, and value classes.
  - FreeBuilder - Automatically generates the Builder pattern.
  - JavaPoet - API to generate source files.
  - JHipster - Yeoman source code generator for Spring Boot and AngularJS.
  - Lombok - Code generator that aims to reduce verbosity.
- GUI
  - JavaFX - Successor of Swing.
  - Scene Builder - Visual layout tool for JavaFX applications.
  - SWT - Graphical widget toolkit.
- IDE
  - Visual Studio Code - Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace.
  - IntelliJ IDEA ![c - Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.
- ORM
  - Doma 2 - Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.
  - Doma 2 - Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.
  - SimpleFlatMapper - Simple database and CSV mapper.
  - Apache Cayenne - Provides a clean, static API for data access. Also includes a GUI Modeler for working with database mappings, and DB reverse engineering and generation.
  - Doma 2 - Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.
  - 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. (LGPL-2.1-only)
  - MyBatis - Couples objects with stored procedures or SQL statements.
- Platform
  - Logging - Wrapper around a variety of logging API implementations.
  - Orienteer - Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.
  - BCEL - Byte Code Engineering Library - analyze, create, and manipulate Java class files.
  - BeanUtils - Easy-to-use wrappers around the Java reflection and introspection APIs.
  - BeanUtils2 - Redesign of Commons BeanUtils.
  - BSF - Bean Scripting Framework - interface to scripting languages, including JSR-223.
  - Chain - Chain of Responsibility pattern implementation.
  - ClassScan - Find Class interfaces, methods, fields, and annotations without loading.
  - CLI - Command-line arguments parser.
  - CLI2 - Redesign of Commons CLI.
  - Codec - General encoding/decoding algorithms, e.g. phonetic, base64 or URL.
  - Collections - Extends or augments the Java Collections Framework.
  - Compress - Defines an API for working with tar, zip and bzip2 files.
  - Configuration - Reading of configuration/preferences files in various formats.
  - Convert - Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another.
  - CSV - Component for reading and writing comma separated value files.
  - Daemon - Alternative invocation mechanism for unix-daemon-like java code.
  - DBCP - Database connection pooling services.
  - DbUtils - JDBC helper library.
  - Digester - XML-to-Java-object mapping utility.
  - Email - Library for sending e-mail from Java.
  - Exec - API for dealing with external process execution and environment management in Java.
  - FileUpload - File upload capability for your servlets and web applications.
  - Finder - Java library inspired by the UNIX find command.
  - Math - Lightweight, self-contained mathematics and statistics components.
  - Spring - Provides many packages for dependency injection, aspect-oriented programming, security, etc.
- Science
  - Morpheus - Provides a versatile two-dimensional memory efficient tabular data structure called a DataFrame to enable efficient in-memory analytics for scientific computing on the JVM.
  - DataMelt - Environment for scientific computation, data analysis and data visualization. (GPL-3.0-or-later)
  - Morpheus - Provides a versatile two-dimensional memory efficient tabular data structure called a DataFrame to enable efficient in-memory analytics for scientific computing on the JVM.
  - Tablesaw - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.
  - Erdos - Modular, light and easy graph framework for theoretic algorithms.
  - JGraphT - Graph library that provides mathematical graph-theory objects and algorithms.
  - JGraphX - Library for visualizing (mainly Swing) and interacting with node-edge graphs.
  - Mines Java Toolkit - Library for geophysical scientific computation, visualization and digital signal analysis.
  - Orson-Charts - Generates a wide variety of 3D charts that can be displayed with Swing and JavaFX or exported to PDF, SVG, PNG and JPEG. (GPL-3.0-only)
  - XChart - Light-weight library for plotting data. Many customizable chart types are available.
  - GraphStream - Library for modeling and analyzing dynamic graphs.
  - JFreeChart - 2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)
- Security
  - Bouncy Castle - All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.
  - Themis - Multi-platform high-level cryptographic library provides easy-to-use encryption for protecting sensitive data: secure messaging with forward secrecy, secure data storage (AES256GCM); suits for building end-to-end encrypted applications.
  - Bouncy Castle - All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.
  - Hdiv - Runtime application that repels application security risks included in the OWASP Top 10, including SQL injection, cross-site scripting, cross-site request forgery, data tampering, and brute force attacks.
  - jjwt - JSON web token for Java and Android.
  - Jwks RSA - JSON Web Key Set parser.
  - Kalium - Binding for the Networking and Cryptography (NaCl) library.
  - Keywhiz - System for distributing and managing secrets.
  - Nbvcxz - Advanced password strength estimation.
  - OACC - Provides permission-based authorization services.
  - pac4j - Security engine.
  - SecurityBuilder - Fluent Builder API for JCA and JSSE classes and especially X.509 certificates.
  - Tink - Provides a simple and misuse-proof API for common cryptographic tasks.
  - Vault - Secures, stores, and tightly controls access to tokens, passwords, certificates, API keys, and other secrets. It handles leasing, key revocation, key rolling, and auditing. Through a unified API, users can access an encrypted Key/Value store and network encryption-as-a-service, or generate AWS IAM/STS credentials, SQL/NoSQL databases, X.509 certificates, SSH credentials, and more.
  - Keycloak - Integrated SSO and IDM for browser apps and RESTful web services.
  - Apache Shiro - Performs authentication, authorization, cryptography and session management.
  - Cryptomator - Multiplatform, transparent, client-side encryption of files in the cloud. (GPL-3.0-only)
- Reactive libraries
  - Reactor - Library for building reactive fast-data applications.
  - Akka - Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.
  - Reactive Streams - Provides a standard for asynchronous stream processing with non-blocking backpressure.
  - RxJava - Allows for composing asynchronous and event-based programs using observable sequences.
  - vert.x - Polyglot event-driven application framework.
- REST Frameworks
  - Elide - Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.
  - javalin - Javalin is just a few thousand lines of code on top of Jetty, which means its performance is almost equivalent to pure Jetty.
  - RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - Dropwizard - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
  - Microserver - A convenient, extensible microservices plugin system for Spring & Spring Boot. With more than 30 plugins and growing, it supports both micro-monolith and pure microservices styles.
  - rest.li - Framework for building robust, scalable RESTful architectures using typesafe bindings and asynchronous, non-blocking IO with an end-to-end developer workflow that promotes clean practices, uniform interface design and consistent data modeling.
  - RestExpress - Thin wrapper on the JBoss Netty HTTP stack that provides scaling and performance.
  - Restlet Framework - Pioneering framework with powerful routing and filtering capabilities, and a unified client and server API.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
  - springdoc-openapi - Automates the generation of API documentation using Spring Boot projects.
  - Dropwizard - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
  - Jersey - JAX-RS reference implementation.
  - Rapidoid - Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.
  - Spark - Sinatra inspired framework.
  - Swagger - Standard, language-agnostic interface to REST APIs.
  - Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
- Search
  - Apache Solr - Enterprise search engine optimized for high-volume traffic.
  - Indexer4j - Simple and light full text indexing and searching library.
  - Apache Lucene - High-performance, full-featured, cross-platform, text search engine library.
  - Elasticsearch - Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.
- Template Engine
  - Jtwig - Modular, configurable and fully tested template engine.
  - Jtwig - Modular, configurable and fully tested template engine.
  - Jade4J - Implementation of Pug (formerly known as Jade).
  - Rocker - Optimized, memory efficient and speedy template engine producing statically typed, plain objects.
  - Handlebars.java - Logicless and semantic Mustache templates.
  - Pebble - Inspired by Twig and separates itself with its inheritance feature and its easy-to-read syntax. It ships with built-in autoescaping for security and it includes integrated support for internationalization.
  - Thymeleaf - Aims to be a substitute for JSP and works for XML files.
- Version Managers
  - jenv - Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and macOS.
  - jabba - Java Version Manager inspired by nvm. Supports macOS, Linux and Windows.
  - SDKMan - Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms and Windows.
- Development
  - NoException - Allows checked exceptions in functional interfaces and converts exceptions to Optional return.
  - Faux Pas - Library that simplifies error handling by circumventing the issue that none of the functional interfaces in the Java Runtime is allowed by default to throw checked exceptions.
  - HotswapAgent - Unlimited runtime class and resource redefinition. (GPL-2.0-only)
  - JavaParser - Parse, modify and generate Java code.
  - JavaSymbolSolver - Symbol solver.
  - Manifold - Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.
  - SneakyThrow - Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations.
  - DCEVM - JVM modification that allows unlimited redefinition of loaded classes at runtime. (GPL-2.0-only)
- Native
  - JavaCPP - Provides efficient and easy access to native C++.
  - 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](http://openjdk.java.net/projects/panama).
- Natural Language Processing
  - Beagle - Stored full-text search query engine.
  - CogCompNLP - Provides common annotators for plain text input. (Research and Academic Use License)
  - Lingua - Natural language detection library, especially suited for short paragraphs of text.
  - LingPipe - Toolkit for tasks ranging from POS tagging to sentiment analysis.
  - CoreNLP - Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis. (GPL-3.0-or-later)
  - DKPro - Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.
- Networking
  - AkkaGRPC - Support for building streaming gRPC servers and clients on top of Akka Streams.
  - Comsat - Integrates standard Java web-related APIs with Quasar fibers and actors.
  - Finagle - Extensible RPC system for constructing high-concurrency servers. It implements uniform client and server APIs for several protocols, and is protocol-agnostic to simplify implementation of new protocols.
  - gRPC - RPC framework based on protobuf and HTTP/2.
  - KryoNet - Provides a clean and simple API for efficient TCP and UDP client/server network communication using NIO and Kryo.
  - Nifty - Implementation of Thrift clients and servers on Netty.
  - ServiceTalk - Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.
  - sshj - Programatically use SSH, SCP or SFTP.
  - TLS Channel - Implements a ByteChannel interface over SSLEngine, enabling easy-to-use (socket-like) TLS.
  - urnlib - Represent, parse and encode URNs, as in RFC 2141. (GPL-3.0-only)
  - Dubbo - High-performance RPC framework.
  - Grizzly - NIO framework. Used as a network layer in Glassfish.
  - MINA - Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.
  - Netty - Framework for building high-performance network applications.
  - Nifty - Implementation of Thrift clients and servers on Netty.
  - Undertow - Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly. (LGPL-2.1-only)
- PaaS
  - Google Cloud ![c - Google's cloud infrastructure.
  - Heroku ![c - Abstract computing environments.
- Performance analysis
  - honest-profiler - Low-overhead, bias-free sampling profiler.
  - jHiccup - Logs and records platform JVM stalls.
  - JITWatch - Analyze the JIT compiler optimisations made by the HotSpot JVM.
  - LatencyUtils - Utilities for latency measurement and reporting.
  - JMH - Harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM. (GPL-2.0 only WITH Classpath-exception-2.0)
  - fastThread ![c - Analyze and visualize thread dumps with a free cloud-based upload interface.
  - GCeasy ![c - Tool to analyze and visualize GC logs. It provides a free cloud-based upload interface.
- Processes
  - ch.vorburger.exec - Convenient API around Apache Commons Exec.
  - zt-exec - Provides a unified API to Apache Commons Exec and ProcessBuilder.
  - zt-process-killer - Stops processes started from Java or the system processes via PID.
- Serialization
  - 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.
  - PHP Serializer - Serializing objects in the PHP serialization format.
- Server
  - nanohttpd - Tiny, easily embeddable HTTP server.
  - Apache Tomcat - Robust, all-round server for Servlet and JSP.
  - Apache TomEE - Tomcat plus Java EE.
  - Jetty - Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations.
  - WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)
- Compiler-compiler
  - JavaCC - Parser generator that generates top-down parsers. Allows lexical state switching and permits extended BNF specifications.
- Constraint Satisfaction Problem Solver
  - JaCoP - Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models. (AGPL-3.0)
- Date and Time
  - iCal4j - Parse and build iCalendar [RFC 5545](https://tools.ietf.org/html/rfc5545) data models.
  - ThreeTen-Extra - Additional date-time classes that complement those in JDK 8.
  - Time4J - Advanced date and time library. (LGPL-2.1-only)
  - Almanac Converter - Simple conversion between different calendar systems.
Resources
- Twitter
  - Aleksey Shipilëv - Performance geek, benchmarking czar, concurrency bug hunter.
  - Antonio Goncalves - Java Champion, JUG Leader, Devoxx France, Java EE 6/7, JCP, Author.
  - Ed Burns - Consulting Member of the Technical Staff at Oracle.
  - Eugen Paraschiv - Author of the Spring Security Course.
  - Aleksey Shipilëv - Performance geek, benchmarking czar, concurrency bug hunter.
  - Brian Goetz - Java Language Architect at Oracle.
  - Bruno Borges - Product Manager/Java Jock at Oracle.
  - Chris Richardson - Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, \*POJOs in Action- author.
  - Ed Burns - Consulting Member of the Technical Staff at Oracle.
  - Eugen Paraschiv - Author of the Spring Security Course.
  - Heinz Kabutz - Java Champion, speaker, author of The Java Specialists' Newsletter, concurrency performance expert.
  - Holly Cummins - Technical Lead of IBM London's Bluemix Garage, Java Champion, developer, author, JavaOne rockstar.
  - James Weaver - Java/JavaFX/IoT developer, author and speaker.
  - Java Magazine - Official Java Magazine account.
  - Javin Paul - Well-known Java blogger.
  - Josh Long - Spring Advocate at Pivotal, author of O'Reilly's Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star.
  - Lukas Eder - Java Champion, speaker, JUG.ch co-leader, Founder and CEO Data Geekery (jOOQ).
  - Mario Fusco - RedHatter, JUG coordinator, frequent speaker and author.
  - Mark Heckler - Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud.
  - Mark Reinhold - Chief Architect, Java Platform Group, Oracle.
  - Markus Eisele - Java EE evangelist, Red Hat.
  - Martijn Verburg - London JUG co-leader, speaker, author, Java Champion and much more.
  - Martin Thompson - Pasty faced performance gangster.
  - Monica Beckwith - Performance consultant, JavaOne Rock Star.
  - OpenJDK - Official OpenJDK account.
  - Peter Lawrey - Peter Lawrey, Java performance expert.
  - Randy Shoup - Stitch Fix VP Engineering, speaker, JavaOne Rock Star.
  - Reza Rahman - Java EE/GlassFish/WebLogic evangelist, author, speaker, open source hacker.
  - Sander Mak - Java Champion, author.
  - Simon Maple - Java Champion, VirtualJUG founder, LJC leader, RebelLabs author.
  - Spencer Gibb - Software Engineer, Dad, Geek, Co-founder and Lead of Spring Cloud Core @pivotal.
  - Stephen Colebourne - Java Champion, speaker.
  - Trisha Gee - Java Champion and speaker.
  - Venkat Subramaniam - Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion.
  - Vlad Mihalcea - Java Champion working on Hypersistence Optimizer, database aficionado, author of High-Performance Java Persistence book.
  - Bruno Borges - Product Manager/Java Jock at Oracle.
  - Chris Richardson - Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, \*POJOs in Action- author.
  - Josh Long - Spring Advocate at Pivotal, author of O'Reilly's Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star.
  - Randy Shoup - Stitch Fix VP Engineering, speaker, JavaOne Rock Star.
  - Java EE - Official Java EE Twitter account.
  - Brian Goetz - Java Language Architect at Oracle.
  - Heinz Kabutz - Java Champion, speaker, author of The Java Specialists' Newsletter, concurrency performance expert.
  - James Weaver - Java/JavaFX/IoT developer, author and speaker.
  - Lukas Eder - Java Champion, speaker, JUG.ch co-leader, Founder and CEO Data Geekery (jOOQ).
  - Mark Heckler - Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud.
  - Mark Reinhold - Chief Architect, Java Platform Group, Oracle.
  - Martijn Verburg - London JUG co-leader, speaker, author, Java Champion and much more.
  - Peter Lawrey - Peter Lawrey, Java performance expert.
  - Stephen Colebourne - Java Champion, speaker.
  - Arun Gupta - Java Champion, JavaOne Rockstar, JUG Leader, Devoxx4Kids-er, VP of Developer Advocacy at Couchbase.
  - Adam Bien - Freelance author, JavaOne Rockstar speaker, consultant, Java Champion.
  - Holly Cummins - Technical Lead of IBM London's Bluemix Garage, Java Champion, developer, author, JavaOne rockstar.
  - Java Magazine - Official Java Magazine account.
  - Java - Official Java Twitter account.
  - Javin Paul - Well-known Java blogger.
  - Mario Fusco - RedHatter, JUG coordinator, frequent speaker and author.
  - Markus Eisele - Java EE evangelist, Red Hat.
  - Martin Thompson - Pasty faced performance gangster.
  - Monica Beckwith - Performance consultant, JavaOne Rock Star.
  - OpenJDK - Official OpenJDK account.
  - Reza Rahman - Java EE/GlassFish/WebLogic evangelist, author, speaker, open source hacker.
  - Sander Mak - Java Champion, author.
  - Simon Maple - Java Champion, VirtualJUG founder, LJC leader, RebelLabs author.
  - Spencer Gibb - Software Engineer, Dad, Geek, Co-founder and Lead of Spring Cloud Core @pivotal.
  - Trisha Gee - Java Champion and speaker.
  - Venkat Subramaniam - Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion.
  - Vlad Mihalcea - Java Champion working on Hypersistence Optimizer, database aficionado, author of High-Performance Java Persistence book.
- Communities
  - r/java - Subreddit for the Java community.
  - Stack Overflow - Question/answer platform.
  - VirtualJUG - Virtual Java User Group.
- Websites
- Awesome Lists
- Frontends
  - java.libhunt.com
- Podcasts and Screencasts
  - The Java Posse - Discontinued as of 02/2015.
  - The Java Council
  - Java Off Heap
  - Marco Behler's Screencasts - Screencasts about modern Java development.
- Influential Books
Contributing
- Websites
  - CONTRIBUTING - java-validation).

Programming Languages

Java 253 Kotlin 6 C++ 4 Scala 3 HTML 2 Clojure 1 JavaScript 1 Gherkin 1 java 1 Go 1

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