awesome-java

ArchUnit

Test library for specifying and asserting architecture rules

jMolecules

Annotations and interfaces to express design and architecture concepts in code

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

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

Declarative build and dependency management that favors convention over configuration. It might be preferable to Apache Ant, which uses a rather procedural approach and can be difficult to maintain

Tool from Google that builds code quickly and reliably

Buck2

Encourages the creation of small, reusable modules consisting of code and resources

Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven's dependency management

All-purpose, low-level bytecode manipulation and analysis

Further simplifies bytecode generation with a fluent API

bytecode-viewer

Java 8 Jar & Android APK reverse engineering suite. (GPL-3.0-only)

Manipulate bytecode at runtime via DSL (rules); mainly for testing/troubleshooting. (LGPL-2.1-or-later)

cglib

Bytecode generation library

Javassist

Tries to simplify bytecode editing

Maker

Provides low level bytecode generation

Mixin

Manipulate bytecode at runtime using real Java code

Perses

Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering

JVM reverse engineering toolkit, essentially an IDE for Java bytecode

In-memory high performance caching library

Caffeine

High-performance, near-optimal caching library

Distributed general-purpose cache

Highly concurrent key/value datastore used for caching

Annotation-based framework for parsing Git-like command-line arguments

Command-line argument-parsing framework with custom types and validation via implementing interfaces

jbock

Reflectionless command line parser

JLine

Includes features from modern shells like completion or history

ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args

Jansi

ANSI escape codes to format console output

Advanced console (and Swing) text user interface (TUI) library, with mouse-draggable windows, built-in terminal window manager, and sixel image support. Looks like

Text-IO

Aids the creation of full console-based applications

Lanterna

Easy console text-GUI library, similar to curses. (LGPL-3.0-only)

Checkstyle

Static analysis of coding conventions and standards. (LGPL-2.1-or-later)

Error Prone

Catches common programming mistakes as compile-time errors

Error Prone Support

Error Prone extensions: extra bug checkers and a large battery of Refaster templates

Infer

Modern static analysis tool for verifying the correctness of code

Static code analysis with Neo4J-based query language. (GPL-3.0-only)

NullAway

Eliminates NullPointerExceptions with low build-time overhead

PMD

Source code analysis for finding bad coding practices

p3c

Provides Alibaba's coding guidelines for PMD, IDEA and Eclipse

RefactorFirst

Identifies and prioritizes God Classes and Highly Coupled classes

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)

Relies on source-code instrumentation instead of bytecode instrumentation

Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)

Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation

ADT4J

JSR-269 code generator for algebraic data types

Auto

Generates factory, service, and value classes

Generates Lightweight JAX-RS style http servers using Javalin or Helidon (Nima) SE

Browser-based Spring Boot app generation with JPA model and REST API

FreeBuilder

Automatically generates the Builder pattern

Geci

Discovers files that need generated code, updates automatically and writes to the source with a convenient API

Annotation processors to generate simple, safe and consistent value objects

JavaPoet

API to generate source files

JHipster

Yeoman source code generator for Spring Boot and AngularJS

Small framework that adds queryable properties to Java, enhancing JavaBeans

Plugin for IntelliJ IDEA. Provides visual tools for generating JPA entities, Spring Data JPA repositories, Liquibase changelogs and SQL scripts. Offers automatic Liquibase/Flyway script generation by comparing model to DB, and reverse engineering JPA entities from DB tables

Code generator that aims to reduce verbosity

Record-Builder

Companion builder class, withers and templates for Java records

Simple and light code generator available as an Eclipse Plugin and also as a CLI

Complex full-featured framework for top-down parsing

Parser generator that generates top-down parsers. Allows lexical state switching and permits extended BNF specifications

Lexical analyzer generator

Library for image processing, camera calibration, tracking, SFM, MVS, 3D vision, QR Code and much more

Medical image processing application with an API

JavaCV

Java interface to OpenCV, FFmpeg, and much more

Loads yaml and properties files, supports dynamic configuration, plugins, file-watching and config event listeners

centraldogma

Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2

config

Configuration library supporting Java properties, JSON or its human optimized superset HOCON

Configurate

Configuration library with support for various configuration formats and transformations

High-level API for Apache ZooKeeper

dotenv

Twelve-factor configuration library which uses environment-specific files

Externalized Properties

Lightweight yet powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism

Gestalt

Gestalt offers a comprehensive solution to the challenges of configuration management. It allows you to source configuration data from multiple inputs, merge them intelligently, and present them in a structured, type-safe manner

Provides an API for handling Windows' INI files

KAConf

Annotation-based configuration system for Java and Kotlin

Configuration system designed for microservices which helps to separate configuration from code. The configuration for different services can have common and specific parts and can be dynamically distributed

owner

Reduces boilerplate of properties

Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques

JaCoP

Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models. (AGPL-3.0)

Business planning and resource scheduling optimization solver

Flexible solver with Spring/Quarkus support and quickstarts for the Vehicle Routing Problem, Maintenance Scheduling, Employee Shift Scheduling and much more

FastCSV

Performance-optimized, dependency-free and RFC 4180 compliant

jackson-dataformat-csv

Jackson extension for reading and writing CSV

Simple CSV parser

Powerful CSV parser with support for Dozer, Joda-Time and Java 8

uniVocity-parsers

One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records

Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs

Fast and efficient columnar storage format for Hadoop-based workloads

Columnar storage format based on assembly algorithms from Google's paper on Dremel

Data interchange format that originated at Facebook

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

RoaringBitmap

Fast and efficient compressed bitmap

SBE

Simple Binary Encoding, one of the fastest message formats around

Tape

Lightning-fast, transactional, file-based FIFO

Wire

Clean, lightweight protocol buffers

Dynamic data management framework. It contains many of the pieces that comprise a typical database management system

Distributed, schema on-the-fly, ANSI SQL query engine for Big Data exploration

High-performance relational database layer over HBase for low-latency applications

ArangoDB

ArangoDB Java driver

Chronicle Map

Efficient, in-memory (opt. persisted to disk), off-heap key-value store

Low latency data streaming platform for change data capture

High-performance, column-oriented, distributed data store

eXist

NoSQL document database and application platform. (LGPL-2.1-only)

FlexyPool

Brings metrics and failover strategies to the most common connection pooling solutions

Simple database migration tool

Small SQL database notable for its in-memory functionality

HikariCP

High-performance JDBC connection pool

HyperSQL 100% Java database

Convenient abstraction of JDBC

Jedis

Small client for interaction with Redis, with methods for commands

Jest

Client for the Elasticsearch REST API

jetcd

Client library for etcd

Jinq

Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ)

Generates typesafe code based on SQL schema

Leaf

Distributed ID generate service

Lettuce is a scalable Redis client for building non-blocking Reactive applications

Database-independent library for tracking, managing and applying database schema changes

Embedded database engine that provides concurrent collections backed on disk or in off-heap memory

MariaDB4j

Launcher for MariaDB that requires no installation or external dependencies

Modality

Lightweight ORM with database reverse engineering features

OpenDJ

LDAPv3 compliant directory service, developed for the Java platform, providing a high performance, highly available, and secure store for the identities

Typesafe unified queries

QueryStream

Build JPA Criteria queries using a Stream-like API

QuestDB

High-performance SQL database for time series. Supports InfluxDB line protocol, PostgreSQL wire protocol, and REST

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

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

Speedment

Database access library that utilizes Java 8's Stream API for querying

Spring Data JPA MongoDB Expressions

Allows you to use MongoDB query language to query your relational database

Distributed SQL query engine for big data

JDBC connection pool library with advanced performance monitoring capabilities

Xodus

Highly concurrent transactional schema-less and ACID-compliant embedded database

CosId

Universal, flexible, high-performance distributed ID generator

iCal4j

Parse and build iCalendar data models

Jollyday

Determines the holidays for a given year, country/name and eventually state/region

ThreeTen-Extra

Additional date-time classes that complement those in JDK 8

Time4J

Advanced date and time library. (LGPL-2.1-only)

CDI extension framework

Microservice-focused compile-time injection framework without reflection

Compile-time injection framework without reflection

Feather

Ultra-lightweight, JSR-330-compliant dependency injection library

Governator

Extensions and utilities that enhance Google Guice

Guice

Lightweight and opinionated framework that completes Dagger

Lightweight and dynamic dependency injection framework

JayWire

Lightweight dependency injection framework. (LGPL-3.0-only)

Seamless aspect-oriented programming extension

JVM modification that allows unlimited redefinition of loaded classes at runtime. (GPL-2.0-only)

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

Allows checked exceptions in functional interfaces and converts exceptions to Optional return

SneakyThrow

Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations

Enable infinite recursion using tail call optimization

In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery

Realtime computation system

Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems

Fault-tolerant distributed coordination framework

Framework for creating CQRS applications

Dropwizard Circuit Breaker

Circuit breaker design pattern for Dropwizard. (GPL-2.0-only)

Failsafe

Simple failure handling with retries and circuit breakers

Hazelcast

Highly scalable in-memory datagrid with a free open-source version

Toolkit for reliable messaging and cluster creation

Lightweight threads and actors for the JVM

resilience4j

Functional fault tolerance library

OpenIG

High-performance reverse proxy server with specialized session management and credential replay functionality

ScaleCube Services

Embeddable Cluster-Membership library based on SWIM and gossip protocol

Zuul

Gateway service that provides dynamic routing, monitoring, resiliency, security, and more

Provides transactions for REST, SOA and microservices with support for JTA and XA

Bitronix

Simple but complete implementation of the JTA 1.1 API

Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards. (LGPL-2.1-only)

Seata

Delivers high performance and easy to use distributed transaction services under a microservices architecture

Artipie

Binary artifact management toolkit which hosts them on the file system or S3

Deployment of JVM applications 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

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

Fully managed package management SaaS with support for Maven/Gradle/SBT with a free tier

Getdown

System for deploying Java applications to end-user computers and keeping them up to date. Developed as an alternative to Java Web Start

Setup authoring tool for cross-platform deployments

JavaPackager

Maven and Gradle plugin which provides an easy way to package Java applications in native Windows, macOS or GNU/Linux executables, and generate installers for them

Deploy desktop apps as native Mac, Windows or Linux bundles

jlink.online

Builds optimized runtimes over HTTP

Binary management with proxy and caching capabilities

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

Supports OOXML (XLSX, DOCX, PPTX) as well as OLE2 (XLS, DOC or PPT)

API for document format conversion using third-party converters such as MS Word

Create and manipulate Microsoft Open XML files

fastexcel

High performance library to read and write large Excel (XLSX) worksheets

zerocell

Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead

Cassandre

Trading bot framework

Parity

Platform for trading venues

Philadelphia

Low-latency financial information exchange

Square

Integration with the Square API

Stripe

Integration with the Stripe API

ta4j

Library for technical analysis

CATG

Concolic unit testing engine. Automatically generates unit tests using formal methods

Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)

Detects likely program invariants and generates JML specs based on those invariants

Java Path Finder (JPF)

JVM formal verification tool containing a model checker and more. Created by NASA

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)

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. (GPL-2.0-or-later)

Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)

Cyclops

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 and morphisms. (GPL-3.0-only)

Functional extensions to Guava

Implements numerous basic and advanced programming abstractions that assist composition-oriented development

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 component library that provides persistent data types and functional control structures

JavaFX Game Development Framework

Port of the renowned C++ 2D physics engine

Game engine for modern 3D development

All-round cross-platform, high-level framework

AWT-based, lightweight 2D game engine

Robust framework that abstracts libraries like OpenGL/CL/AL

Beginner-friendly, master-ready framework for rapidly prototyping and building 2D games

High-level 2D game engine with built-in physics based on Swing

Library for developing geospatial applications

ArcGIS Maps SDK for Java

JavaFX library for adding mapping and GIS functionality to desktop apps

Geo

GeoHash utilities in Java

Library that provides tools for geospatial data. (LGPL-2.1-only)

GraphHopper

Road-routing engine. Used as a Java library or standalone web service

Spatial extension of the H2 database. (LGPL-3.0-only)

Library for using the GeoHash algorithm

Mapsforge

Map rendering based on OpenStreetMap data. (LGPL-3.0-only)

Spatial4j

General-purpose spatial/geospatial library

Successor of Swing

Visual layout tool for JavaFX applications

SnapKit

Modern Java UI library for both desktop and web

Graphical widget toolkit

Agrona

Data structures and utility methods that are common in high-performance applications

Inter-thread messaging library

Eclipse Collections

Collections framework inspired by Smalltalk

Fast and compact type-specific collections

Primitive collections

JCTools

Concurrency tools currently missing from the JDK

Koloboke

Carefully designed extension of the Java Collections Framework with primitive specializations and more

Toolset of low-level Java components focused on HTTP and associated protocols

Async Http Client

Asynchronous HTTP and WebSocket client library

Wrapper on JDK 11's HttpClient that adds Feign-like interface among other enhancements

Feign

HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket

Google HTTP Client

Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf

methanol

HTTP client extensions library

Typesafe REST client

Ribbon

Client-side IPC library that is battle-tested in the cloud

Riptide

Client-side response routing for Spring's RestTemplate

unirest-java

Simplified, lightweight HTTP client library

hate

Builds hypermedia-friendly objects according to HAL specification

JSON-LD

JSON-LD implementation

Siren4J

Library for the Siren specification

Established open-source project with support for lots of plugins and languages

Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector

Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer

Provides integration for several Java SE and EE features, from database access to HTML5

Modern IDE for Java running in the browser, focused on education

Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace

Imgscalr

Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D

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

ZXing

Multi-format 1D/2D barcode image processing library

image-comparison

Library that compares 2 images with the same sizes and shows the differences visually by drawing rectangles. Some parts of the image can be excluded from the comparison

ClassGraph

ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages

jOOR

jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package

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

Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions

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

JobRunr

Job scheduling library which utilizes lambdas for fire-and-forget, delayed and recurring jobs. Guarantees execution by single scheduler instance using optimistic locking. Has features for persistence, minimal dependencies and is embeddable

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

easy-batch

Set up batch jobs with simple processing pipelines. Records are read in sequence from a data source, processed in pipeline and written in batches to a data sink

shedlock

Makes sure that your scheduled tasks are executed at most once at the same time. If a task is being executed on one node, it acquires a lock which prevents execution of the same task from another node or thread

Reflection-free Json binding via source code generation with Jackson-like annotations

DSL-JSON

JSON library with advanced compile time databinding

Powerful and easy-to-use Java-to-JSON conversion library

Gson

Serializes objects to JSON and vice versa. Good performance with on-the-fly usage

HikariJSON

High-performance JSON parser, 2x faster than Jackson

jackson-modules-java8

Set of Jackson modules for Java 8 datatypes and features

Jackson-datatype-money

Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types

Jackson

Similar to GSON, but offers performance gains if you need to instantiate the library more often

JSON-io

Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer

Fast and flexible library with iterator and lazy parsing API

LoganSquare

JSON parsing and serializing library based on Jackson's streaming API. Outperforms GSON & Jackson's library

Moshi

Modern JSON library, less opinionated and uses built-in types like List and Map

Yasson

Binding layer between classes and JSON documents similar to JAXB

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

Community-driven OpenJDK builds, including both HotSpot and OpenJ9

No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)

Dragonwell8

Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications

Graal

Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)

Built from OpenJDK, thoroughly tested and passed the JCK. (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

Open JDK community home. (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's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)

SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)

OpenJDK builds for Windows, Linux, and macOS. (GPL-2.0-only WITH Classpath-exception-2.0)

Microsoft JDK

Microsoft Build of OpenJDK, Free, Open Source, Freshly Brewed!

Complete rewrite with a powerful plugin and configuration architecture

Echopraxia

API designed around structured logging, rich context, and conditional logging. There are Logback and Log4J2 implementations, but Echopraxia's API is completely dependency-free, meaning it can be implemented with any logging API

Open-source aggregator suited for extended role and permission management. (GPL-3.0-only)

Analyzes and visualizes log files. Some features require payment

Robust logging library with interesting configuration options via Groovy

Logbook

Extensible, open-source library for HTTP request and response logging

Tool for managing log files

p6spy

Enables logging for all JDBC transactions without changes to the code

Abstraction layer/simple logging facade

Lightweight logging framework with static logger class

OpenTracing Toolbox

Collection of libraries that build on top of OpenTracing and provide extensions and plugins to existing instrumentations

Flogger is a fluent logging API for Java. It supports a wide variety of features, and has many benefits over existing logging APIs

Fast, reliable, large-scale data processing engine

Scalable algorithms focused on collaborative filtering, clustering and classification

Provides several algorithms and pre-trained models for natural language processing

Distributed and multi-threaded deep learning library

High-level and engine-agnostic framework for deep learning

Analytics engine for statistics over big data

Intelligent java

Seamlessly integrate with remote deep learning and language models programmatically

JSAT

Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)

m2cgen

CLI tool to transpile models into native code

Neureka

A lightweight, platform independent, OpenCL accelerated nd-array/tensor library

High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing

Oryx 2

Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering

Siddhi

Cloud native streaming and complex event processing engine

Smile

Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library

Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow

Collection of algorithms for data mining tasks ranging from pre-processing to visualization. (GPL-3.0-only)

Aeron

Efficient, reliable, unicast and multicast message transport

Message broker that implements JMS and converts synchronous to asynchronous communication

Glues together different transport APIs via Enterprise Integration Patterns

High-throughput distributed messaging system

Distributed pub/sub-messaging system

Fast, reliable, and scalable distributed messaging platform

Apache Qpid makes messaging tools that speak AMQP and support many languages and platforms

AutoMQ

AutoMQ is a cloud-native, serverless reinvented Kafka that is easily scalable, manage-less and cost-effective

Deezpatch

Simple, lightweight, and performant dispatch library for decoupling messages (requests and events) and message handlers

EventBus

Simple publish/subscribe event bus

Fast and reliable message broker built on top of Kafka

JeroMQ

Implementation of ZeroMQ

Nakadi

Provides a RESTful API on top of Kafka

RabbitMQ Java client

RabbitMQ client

Smack

Cross-platform XMPP client library

NATS client

NATS client

Lightweight and fast library for complex high-load distributed applications and Memcached-like solutions

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

Two-style approach for writing microservices: Functional-reactive and as an implementation of MicroProfile

JDA

Wrapping of the Discord REST API and its WebSocket events

Modernized version of a Java-based implementation of the New Typesetting System, which was heavily based on Donald E. Knuth's original TeX

kubernetes-client

Client provides access to the full Kubernetes & OpenShift REST APIs via a fluent DSL

Modern full-stack framework with focus on modularity, minimal memory footprint and startup time

Dynamic service discovery, configuration and service management platform for building cloud native applications

OpenAI-Java

Java libraries for using OpenAI's GPT-3 API

Kubernetes stack tailored for the HotSpot and Graal VM

Sentinel

Flow control component enabling reliability, resilience and monitoring for microservices

AWS SDK for Java 2.0

Wrapper around AWS' API

CQEngine

Ultra-fast, SQL-like queries on Java collections

Design Patterns

Implementation and explanation of the most common design patterns

FF4J

Feature Flags for Java

FizzBuzz Enterprise Edition

No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)

IP2Location.io Java SDK

Wrapper for the IP2Location.io Geolocation API and the IP2WHOIS domain WHOIS API

ISBN core

A small library that contains a representation object of ISBN-10 and ISBN-13 and tools to parse, validate and format one

J2ObjC

Java-to-Objective-C translator for porting Android libraries to iOS

Static website generator

JBot

Framework for building chatbots. (GPL-3.0-only)

JCuda offers Java bindings for CUDA and CUDA-related libraries

Jimfs

In-memory file system

Source code obfuscator

Basic currency and money classes and algorithms not provided by the JDK

jOOX

Simple wrapper for the org.w3c.dom package, to allow for fluent XML document creation and manipulation with an API inspired by jQuery

Snippet runner

jsweet

Source transpiler to TypeScript/JavaScript

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

LittleProxy

High performance HTTP proxy atop Netty's event-based networking library

Modern Java - A Guide to Java 8

Popular Java 8 guide

Modernizer

Detect uses of legacy Java APIs

OctoLinker

Browser extension which allows to navigate through code on GitHub more efficiently

Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases

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

RR4J

RR4J is a tool that records java bytecode execution and later allows developers to replay locally

Simple Java Mail

Mailing with a clean and fluent API

Smooks

Framework for fragment-based message processing. (Apache-2.0 OR LGPL-3.0-or-later)

Svix

Library for the Svix API to send webhooks and verify signatures

Implementation of the Feature Toggles pattern

TypeTools

Tools for resolving generic types

XMLBeam

Processes XML by using annotations or XPath within code

yGuard

Obfuscation via renaming and shrinking

Cross-platform solution for writing native mobile apps. (GPL-2.0-only WITH Classpath-exception-2.0)

Cross-platform framework for developing mobile apps with native UI in Java and Kotlin

Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps

Automon

Combines the power of AOP with monitoring and/or logging tools

Datadog

Modern monitoring & analytics

Dropwizard Metrics

Expose metrics via JMX or HTTP and send them to a database

Failsafe Actuator

Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment

Open-source Java APM

HertzBeat

Real-time monitoring system with custom-monitor and agentless

hippo4j

Dynamic and observable thread pool framework

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

Real-time Java application performance monitoring. A commercial service with free development accounts

Jaeger client

Jaeger client

JavaMelody

Performance monitoring and profiling

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

JMX over REST

Micrometer

Vendor-neutral metrics/observability facade for the most popular metrics/observability libraries

Micrometer Tracing

Vendor-neutral distributed tracing facade for the most popular tracer libraries

nudge4j

Remote developer console from the browser for Java 8 via bytecode injection

OpenTelemetry

Instrument, generate, collect, and export telemetry data to help you analyze your software’s performance and behavior

Pinpoint

Open-source APM tool

Prometheus

Provides a multi-dimensional data model, DSL, autonomous server nodes and much more

Sentry

Integration with , an application error tracking and performance analysis platform

SPM

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

Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures

Aparapi

Converts bytecode to OpenCL which allows execution on GPUs

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

native-lib-loader

Native library loader for extracting and loading native libraries from Java

CogCompNLP

Provides common annotators for plain text input. (Research and Academic Use License)

Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis. (GPL-3.0-or-later)

Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc

Toolkit for tasks ranging from POS tagging to sentiment analysis

Commons-networking

Client for server-sent events (SSE)

Comsat

Integrates standard Java web-related APIs with Quasar fibers and actors

Dubbo

High-performance RPC framework

NIO framework. Used as a network layer in Glassfish

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

Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO

Framework for building high-performance network applications

Drift

Easy-to-use, annotation-based library for creating Thrift clients and serializable types

ServiceTalk

Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms

sshj

Programmatically use SSH, SCP or SFTP

TLS Channel

Implements a ByteChannel interface over SSLEngine, enabling easy-to-use (socket-like) TLS

Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly. (LGPL-2.1-only)

urnlib

Represent, parse and encode URNs, as in RFC 2141. (GPL-3.0-only)

Fluency

High throughput data ingestion logger to Fluentd and Fluent Bit

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

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

Provides simple and fast data access

Supports a number of persistence standards: JPA, JAXB, JCA and SDO

Robust and widely used, with an active community. (LGPL-2.1-only)

MyBatis

Couples objects with stored procedures or SQL statements

ObjectiveSql

ActiveRecord ORM for rapid development and convention over configuration

Permazen

Language-natural persistence layer

SimpleFlatMapper

Simple database and CSV mapper

AWS-based, with support for Tomcat and Jetty

Serverless computation

Google's cloud infrastructure

Abstract computing environments

Microsoft's cloud infrastructure

Provides additionally an on-premise solution

Creates PDFs from XSL-FO

Toolbox for creating and manipulating PDFs

Abstraction layer to JasperReports. (LGPL-3.0-only)

DynamicReports

Simplifies JasperReports. (LGPL-3.0-only)

Report engine for creating PDF and other formats (DOCX, XLSX, HTML, etc) using Eclipse-based visual editor

flyingsaucer

XML/XHTML and CSS 2.1 renderer. (LGPL-2.1-or-later)

Creates PDF files programmatically

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)

Tabula

Extracts tables from PDF files

Analyze and visualize thread dumps with a free cloud-based upload interface

Tool to analyze and visualize GC logs. It provides a free cloud-based upload interface

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

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)

LatencyUtils

Utilities for latency measurement and reporting

Byte Code Engineering Library - analyze, create, and manipulate Java class files

Easy-to-use wrappers around the Java reflection and introspection APIs

Redesign of Commons BeanUtils

Bean Scripting Framework - interface to scripting languages, including JSR-223

Chain of Responsibility pattern implementation

Find Class interfaces, methods, fields, and annotations without loading

Command-line arguments parser

Redesign of Commons CLI

General encoding/decoding algorithms, e.g. phonetic, base64 or URL

Extends or augments the Java Collections Framework

Defines an API for working with tar, zip and bzip2 files

Reading of configuration/preferences files in various formats

Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another

Component for reading and writing comma separated value files

Alternative invocation mechanism for unix-daemon-like java code

Database connection pooling services

JDBC helper library

XML-to-Java-object mapping utility

Library for sending e-mail from Java

API for dealing with external process execution and environment management in Java

File upload capability for your servlets and web applications

Java library inspired by the UNIX find command

Java library for working with flat data structures

Function that can be manipulated as an object, or an object representing a single, generic function

General purpose graph APIs and algorithms

Adds the feature of localized message bundles that consist of one or many localized texts that belong together

Id is a component used to generate identifiers

Image library

Collection of I/O utilities

Continuation implementation to capture the state of the application

Java Compiler Interface

Java Caching System

XML based scripting and processing engine

Expression language which extends the Expression Language of the JSTL

JNet allows to use dynamically register url stream handlers through the java.net API

Utilities for manipulating Java Beans using the XPath syntax

Provides extra functionality for classes in java.lang

Wrapper around a variety of logging API implementations

Lightweight, self-contained mathematics and statistics components

Monitoring aims to provide a simple but extensible monitoring solution for Java applications

Nabla provides automatic differentiation classes that can generate derivative of any function implemented in the Java language

Collection of network utilities and protocol implementations

Object-graph navigation language

Interface to signing and verifying data using OpenPGP

Small framework for microbenchmark clients, with implementations for Commons DBCP and Pool

Provides a set of pipeline utilities designed around work queues that run in parallel to sequentially process data objects

Generic object pooling component

Library for creating dynamic proxies

Common implementation of RDF 1.1 that could be implemented by systems on the JVM

Commons Rng provides implementations of pseudo-random numbers generators

Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine

Framework to define validators and validation rules in an xml file

Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system

Provides an easy way to enhance (weave) compiled bytecode

High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin

Light-4J

Fast, lightweight and productive microservices framework with built-in

Orienteer

Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications

Provides many packages for dependency injection, aspect-oriented programming, security, etc

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

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

Reactor

Library for building reactive fast-data applications

RxJava

Allows for composing asynchronous and event-based programs using observable sequences

Polyglot event-driven application framework

Dropwizard

Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics

Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model

JAX-RS reference implementation

Microserver

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

Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection

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

Fully certified and portable implementation of the JAX-RS specification

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

Sinatra inspired framework

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

Standard, language-agnostic interface to REST APIs

Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics

Chart-FX

Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets

Environment for scientific computation, data analysis and data visualization. (GPL-3.0-or-later)

Erdos

Modular, light and easy graph framework for theoretic algorithms

Library for modeling and analyzing dynamic graphs

2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)

JGraphT

Graph library that provides mathematical graph-theory objects and algorithms

JGraphX

Library for visualizing (mainly Swing) and interacting with node-edge graphs

LogicNG

Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas

Mines Java Toolkit

Library for geophysical scientific computation, visualization and digital signal analysis

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

A low level space flight dynamics library providing basic elements (orbits, dates, attitude, frames...) and various algorithms (conversions, propagations, pointing...) to handle them

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)

Tablesaw

Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data

XChart

Light-weight library for plotting data. Many customizable chart types are available

High-performance, full-featured, cross-platform, text search engine library

Enterprise search engine optimized for high-volume traffic

Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents

Indexer4j

Simple and light full text indexing and searching library

Performs authentication, authorization, cryptography and session management

All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations

DependencyCheck

Detects publicly disclosed vulnerabilities contained within a project's dependencies

Multiplatform, transparent, client-side encryption of files in the cloud. (GPL-3.0-only)

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

jwt-java

Easily create and parse JSON Web Tokens and create customized JWT validators using a fluent API

Jwks RSA

JSON Web Key Set parser

Kalium

Binding for the Networking and Cryptography (NaCl) library

Integrated SSO and IDM for browser apps and RESTful web services

Keywhiz

System for distributing and managing secrets

Nbvcxz

Advanced password strength estimation

Provides permission-based authorization services

OpenAM

Access management solution that includes authentication, SSO, authorization, federation, entitlements and web services security

OTP-Java

One-time password generator library according to RFC 4226 (HOTP) and RFC 6238 (TOTP)

pac4j

Security engine

Enforce password policy by validating candidate passwords against a configurable rule set

Password4j

User-friendly cryptographic library that supports Argon2, Bcrypt, Scrypt, PBKDF2 and various other cryptographic hash functions

SecurityBuilder

Fluent Builder API for JCA and JSSE classes and especially X.509 certificates

SSLContext-Kickstart

High-level SSL context builder for configuring HTTP clients with SSL/TLS

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

Tink

Provides a simple and misuse-proof API for common cryptographic tasks

Fine-grained authorization for applications with support for RBAC, ABAC, and ReBAC

FlatBuffers

Memory-efficient serialization library that can access serialized data without unpacking and parsing it

FST

JDK-compatible, high-performance object graph serialization

Fury

Blazing fast object graph serialization framework powered by JIT and zero-copy

Kryo

Fast and efficient object graph serialization framework

MessagePack

Efficient binary serialization format

PHP Serializer

Serializing objects in the PHP serialization format

Robust, all-round server for Servlet and JSP

Tomcat plus Java EE

Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations

nanohttpd

Tiny, easily embeddable HTTP server

Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)

Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data

Logicless and semantic Mustache templates

Jade4J

Implementation of Pug (formerly known as Jade)

Jamal

Extendable template engine embedded into Maven/JavaDoc, supporting multiple extensions (Groovy, Ruby, JavaScript, JShell, PlantUml) with support for snippet handling

jstachio

Typesafe Mustache templating engine

jte

Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint

Jtwig

Modular, configurable and fully tested template engine

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

Rocker

Optimized, memory efficient and speedy template engine producing statically typed, plain objects

StringTemplate

Template engine for generating source code, web pages, emails, or any other formatted text output

Aims to be a substitute for JSP and works for XML files

Awaitility

DSL for synchronizing asynchronous operations

ConcurrentUnit

Toolkit for testing multi-threaded and asynchronous applications

In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL. (GPL-2.0-only)

Hoverfly Java

Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services

Karate

DSL that combines API test-automation, mocks and performance-testing making testing REST/HTTP services easy

REST Assured

DSL for easy testing of REST/HTTP services

WebTau

Test across REST-API, Graph QL, Browser, Database, CLI and Business Logic with consistent set of matchers and concepts

Cucumber

Provides a way to describe features in a plain language which customers can understand

Cukes-REST

Collection of Gherkin steps for REST-service testing using Cucumber

J8Spec

Follows a Jasmine-like syntax

Extensively configurable framework that describes stories

Provides a fluent API which allows for simpler composition

Lamdba Behave

Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English

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

Beanmother

Sets up beans from YAML fixtures

Datafaker

Modern fake data generator forked from Java Faker

Fixture Factory

Generates fake objects from a template

jFairy

Fake data generator

Instancio

Automates data setup in unit tests by generating fully-populated, reproducible objects. Includes JUnit 5 extension

Randomized Testing

JUnit test runner and plugins for running JUnit tests with pseudo-randomness

Java Faker

Port of Ruby's fake data generator

Mockneat

Another fake data generator

Functional testing and performance measurements

Integration and functional testing platform for Java EE containers

cdi-test

JUnit extension for easy and efficient testing of CDI components

Integration testing framework that focuses on both client- and server-side messaging

Load testing tool designed for ease of use, maintainability and high performance

Common testing framework

Engine for property-based testing built on JUnit 5

Pact JVM

Consumer-driven contract testing

Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites

weld-testing

Set of test framework extensions (JUnit 4, JUnit 5, Spock) to enhance the testing of CDI components via Weld. Supports Weld 5

Fluent assertions that improve readability

Matchers that can be combined to create flexible expressions of intent

Simplifies testing JSON strings

JsonUnit

Library that simplifies JSON comparison in tests

Google's fluent assertion and proposition framework

XMLUnit

Simplifies testing for XML output

ConsoleCaptor

Captures console output for unit testing purposes

junit-dataprovider

TestNG-like data provider/runner for JUnit

LogCaptor

Captures log entries for unit testing purposes

log-capture

Captures log entries and provides assertions for unit and integration testing

Mutability Detector

Reports whether instances of a given class are immutable

Automatically performs tests on basic POJO methods. (LGPL-3.0-only)

raml-tester

Tests if a request/response matches a given RAML definition

Selfie

Snapshot testing (inline and on disk)

Testcontainers

Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container

Integration testing, API mocking and faking, and code coverage

Mockito

Mocking framework that lets you write tests with a clean and simple API

Allows mocking of systems integrated with HTTPS

Moco

Concise web services for stubs and mocks

PowerMock

Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers

Stubs and mocks web services

EasyMock

EasyMock is a Java library that provides an easy way to use Mock Objects in unit testing

Arthas

Allows to troubleshoot production issues for applications without modifying code or restarting servers

bucket4j

Rate limiting library based on token-bucket algorithm

cactoos

Collection of object-oriented primitives

Chocotea

Generates postman collection, environment and integration tests from java code

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

dregex

Regular expression engine that uses deterministic finite automata. It supports some Perl-style features and yet retains linear matching time, and also offers set operations

Embulk

Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services

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)

Guava

Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more

Framework and environment for building and debugging multi-agent systems. (LGPL-2.0-only)

Utilities for text or data comparison and patching

JavaVerbalExpressions

Library that helps with constructing difficult regular expressions

Lightweight, pure Java library implementing the Git version control system

JKScope

Java scope functions inspired by Kotlin

minio-java

Provides simple APIs to access any Amazon S3-compatible object storage server

Provides an ontology editor and a framework to build knowledge-based systems

Semver4j

Lightweight library that helps you handling semantic versioning with different modes

Underscore-java

Port of Underscore.js functions

jabba

Java Version Manager inspired by nvm. Supports macOS, Linux and Windows

jenv

Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and macOS

SDKMan

Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms and Windows

Highly extensible, highly scalable web crawler for production environments

Crawler4j

Simple and lightweight web crawler

Scrapes, parses, manipulates and cleans HTML

SDK for building low-latency and scalable web crawlers

webmagic

Scalable crawler with downloading, url management, content extraction and persistent

Lightweight asynchronous framework built from the ground up for developing high-performance web applications

Component-oriented framework for creating dynamic, robust, highly scalable web applications

Component-based web application framework similar to Tapestry, with a stateful GUI

Blade

Lightweight, modular framework that aims to be elegant and simple

Minimally opinionated framework for runnable apps

Asynchronous framework for rapid development of high-performance web application

Microframework for web applications

Scalable, fast and modular micro-framework that offers multiple programming models

Full-stack web framework

Small, highly modularized, Sinatra-like framework

Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala

JSF framework with both free and commercial/support versions and frontend components

Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications

Takes

Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability

Full-stack open-source Java framework that simplifies web app development. Build complex, interactive applications with Java alone, and enhance with TypeScript and React components, without needing deep JavaScript, CSS, or HTML expertise

Stateful code platform from Uber

flowable

Compact and efficient workflow and business process management platform

Microservice orchestration platform, forked from Cadence but gRPC based

Subreddit for the Java community

Question/answer platform

Short videos on Twitter explaining Java debugging in depth

(Official)

Discontinued as of 02/2015

Freelance author, JavaOne Rockstar speaker, consultant, Java Champion

Performance geek, benchmarking czar, concurrency bug hunter

Java Champion, JUG Leader, Devoxx France, Java EE 6/7, JCP, Author

Java Champion, JavaOne Rockstar, JUG Leader, Devoxx4Kids-er, VP of Developer Advocacy at Couchbase

Java Language Architect at Oracle

Product Manager/Java Jock at Oracle

Open Source Enthusiast, Speaker, Developer, Developer Advocacy at TimescaleDB

Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, *POJOs in Action- author

Consulting Member of the Technical Staff at Oracle

Author of the Spring Security Course

Java Champion, speaker, author of The Java Specialists' Newsletter, concurrency performance expert

Technical Lead of IBM London's Bluemix Garage, Java Champion, developer, author, JavaOne rockstar

Java/JavaFX/IoT developer, author and speaker

Official Java EE Twitter account

Official Java Magazine account

Official Java Twitter account

Well-known Java blogger

Spring Advocate at Pivotal, author of O'Reilly's Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star

Java Champion, speaker, Founder and CEO Data Geekery (jOOQ)

Java champion, Polyglot, Software Crafter involved with @graalvm, AI/ML/DL, Data Science, Developer communities, speaker & blogger. Creator of couple of awesome lists like this one

RedHatter, JUG coordinator, frequent speaker and author

Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud

Chief Architect, Java Platform Group, Oracle

Java EE evangelist, Red Hat

London JUG co-leader, speaker, author, Java Champion and much more

Pasty faced performance gangster

Performance consultant, JavaOne Rock Star

Official OpenJDK account

Peter Lawrey, Java performance expert

Stitch Fix VP Engineering, speaker, JavaOne Rock Star

Java EE/GlassFish/WebLogic evangelist, author, speaker, open source hacker

Java Champion, author

Java Champion, VirtualJUG founder, LJC leader, RebelLabs author

Software Engineer, Dad, Geek, Co-founder and Lead of Spring Cloud Core @pivotal

Java Champion, speaker

Java Champion and speaker

Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion

Java Champion working on Hypersistence Optimizer, database aficionado, author of High-Performance Java Persistence book

Oracle ACEs, Groundbreaker Ambassadors and Java Champions