japicmp

Apache-2.0 🟢Compares two library JARs and reports source- and binary-incompatible changes.

Revapi

Apache-2.0 🟠Extensible API analysis and change tracking with configurable source, binary and semantic compatibility checks.

Roseau

MIT 🟢Detects source- and binary-breaking changes by comparing library versions from JAR files or source code.

ArchUnit

Apache-2.0 🟢Test library for specifying and asserting architecture rules.

jMolecules

Apache-2.0 🟠Annotations and interfaces to express design and architecture concepts in code.

jQAssistant

GPL-3.0 🟢Static code analysis with Neo4J-based query language.

Taikai

MIT 🟢ArchUnit extension with predefined architecture rules for common Java technologies.

WireDoctor

Apache-2.0 🟢Runtime diagnostic for Spring Boot apps that detects cyclic bean dependencies and slow beans, with CI regression gates.

A2A Java SDK

Apache-2.0 🟢Official Java SDK for the Agent2Agent protocol.

AgentScope Java

Apache-2.0 🟢Framework for building distributed, long-running AI agents with tool execution, persistence and multi-agent orchestration.

Anahata ASI

Apache-2.0 🟢Java agent container with local LLM adapters, stateful tool execution, context management and IDE integration.

ARA

Apache-2.0 🟢Java framework for AI agents with tool calling, deterministic input and output contracts, and configurable execution strategies.

Dokimos

MIT 🟢Evaluation framework for LLM and AI-agent applications that scores responses, validates tool calls and execution traces, and catches quality regressions in CI.

Google Gen AI Java SDK

Apache-2.0 🟢Official Java SDK for integrating Google generative AI models.

JADE

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

JamJet

Apache-2.0 🟢Agent runtime with a Java SDK for building AI agents, supporting graph-based workflow orchestration, multi-agent coordination, and MCP/A2A protocols.

LangChain4j

Apache-2.0 🟢Simplifies integration of LLMs with unified APIs and a comprehensive toolbox.

liter-llm

MIT 🟢Provides a Java binding for a unified LLM API client across multiple providers.

MCP Java SDK

MIT 🟢Enables applications to interact with AI models and tools through a standardized interface (i.e. Model Context Protocol), supporting both synchronous and asynchronous communication patterns.

Protégé

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

Regulus

MIT 🟢Google ADK plugin suite that adds runtime compliance profiles, audit envelopes and GRC adapters for regulated Java AI agents.

simple-openai

MIT 🔴Library to use the OpenAI API (and compatible ones) in the simplest possible way.

Spring AI

Apache-2.0 🟢Application framework for AI engineering for Spring.

Spring AI Alibaba

Apache-2.0 🟢Agentic AI framework built on Spring AI with model, tool, RAG and workflow integrations.

Immuto

🟢Annotation processor that generates type-safe mapper implementations for Java Records using canonical constructors, with zero runtime reflection.

MapStruct

🟢Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.

ModelMapper

Apache-2.0 🟠Intelligent object mapping library that automatically maps objects to each other.

reMap

Apache-2.0 🟢Lambda and method handle-based mapping which requires code and not annotations if objects have different names.

JBot

GPL-3.0 🟠Framework for building chatbots.

JDA

Apache-2.0 🟢Wrapping of the Discord REST API and its WebSocket events.

Nyagram

MIT 🟢Reactive, type-safe framework for Telegram bots based on Spring Boot 3 and Java 21.

TelegramBots

MIT 🟢Java library for building bots with the Telegram Bot API.

Apache Maven

Apache-2.0 🟢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.

Bazel

Apache-2.0 🟢Tool from Google that builds code quickly and reliably.

Buck2

Apache-2.0 🟢Encourages the creation of small, reusable modules consisting of code and resources.

Dependency Analysis Gradle Plugin

Apache-2.0 🟢Analyzes JVM and Android builds and recommends dependency and plugin changes.

Docker Maven Plugin

Apache-2.0 🟢Builds and runs Docker images from Maven.

Eclipse JKube

EPL-2.0 🟢Maven and Gradle plugins for building and deploying Java applications on Kubernetes.

Frontend Maven Plugin

Apache-2.0 🟢Installs and runs Node.js frontend tooling from Maven builds.

git-commit-id Maven Plugin

LGPL-3.0 🟢Exposes Git revision information to Maven builds and applications.

Gradle

Apache-2.0 🟢Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven's dependency management.

jar-cart

MIT 🟢A modern, zero-configuration package manager and runner for the Java ecosystem written in Go, focusing on developer productivity and build speed.

Javadoc Publisher

Apache-2.0 🟠Generate Javadoc from your maven/gradle project and deploy it automatically on GitHub Page.

Jib

Apache-2.0 🟢Builds optimized container images for Java applications without a Docker daemon.

Maven Wrapper

Apache-2.0 🟢Analogue of Gradle Wrapper for Maven, allowing projects to build without a preinstalled Maven.

Polyglot for Maven

EPL-1.0 🟢Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.

ReleaseRun

MIT 🟠Dependency health checker for pom.xml and Gradle projects that scans for CVEs and outdated packages.

Shadow

Apache-2.0 🟢Gradle plugin for creating and transforming executable fat JARs.

ASM

All-purpose, low-level bytecode manipulation and analysis.

Byte Buddy

Apache-2.0 🟢Further simplifies bytecode generation with a fluent API.

bytecode-viewer

GPL-3.0 🟢Java 8 Jar & Android APK reverse engineering suite.

Byteman

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

Javassist

🟢Tries to simplify bytecode editing.

Maker

Apache-2.0 🟢Provides low level bytecode generation.

Recaf

MIT 🟢JVM reverse engineering toolkit, essentially an IDE for Java bytecode.

cache2k

Apache-2.0 🔴In-memory high performance caching library.

Caffeine

Apache-2.0 🟢High-performance, near-optimal caching library.

Ehcache

Apache-2.0 🟢Distributed general-purpose cache.

Infinispan

Apache-2.0 🟢Highly concurrent key/value datastore used for caching.

JetCache

Apache-2.0 🟢Java cache framework with local and distributed caching, annotations and asynchronous APIs.

Airline

Apache-2.0 🟢Annotation-based framework for parsing Git-like command-line arguments.

jbock

MIT 🟢Reflectionless command line parser.

JCommander

Apache-2.0 🟢Command-line argument-parsing framework with custom types and validation via implementing interfaces.

JLine

🟢Includes features from modern shells like completion or history.

picocli

Apache-2.0 🟢ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.

AliveJTUI

🟠Declarative, React-style TUI library for building terminal UIs as component trees with diff-based rendering, focus management, and themes.

Jansi

Apache-2.0 🟠ANSI escape codes to format console output.

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.

Lanterna

LGPL-3.0 🟢Easy console text-GUI library, similar to curses.

AWS SDK for Java 2.x

Apache-2.0 🟢Official Java APIs for interacting with Amazon Web Services.

Google Cloud Client Libraries

Apache-2.0 🟢Client libraries for accessing Google Cloud services from Java applications.

Java Operator SDK

Apache-2.0 🟢SDK for implementing Kubernetes operators in Java.

Kubernetes Java Client

Apache-2.0 🟢Official Java client for the Kubernetes API.

kubernetes-client

Apache-2.0 🟢Client provides access to the full Kubernetes & OpenShift REST APIs via a fluent DSL.

minio-java

Apache-2.0 🟢Provides simple APIs to access any Amazon S3-compatible object storage server.

Checkstyle

LGPL-2.1 🟢Static analysis of coding conventions and standards.

Error Prone

Apache-2.0 🟢Catches common programming mistakes as compile-time errors.

Error Prone Support

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

Infer

MIT 🟢Modern static analysis tool for verifying the correctness of code.

JSpecify

Apache-2.0 🟢Standardized nullness annotations designed to work uniformly across various Java IDEs, compilers, and static analysis tools.

Modernizer

Apache-2.0 🟢Detect uses of legacy Java APIs.

Mutability Detector

Apache-2.0 🟠Reports whether instances of a given class are immutable.

NullAway

MIT 🟢Eliminates NullPointerExceptions with low build-time overhead.

OpenRewrite

Apache-2.0 🟢Automates large-scale source-code refactoring through reusable recipes.

OpenTaint

Apache-2.0 🟢Interprocedural taint analyzer for Java and Spring applications with reusable security rules and dependency models.

PMD

🟢Source code analysis for finding bad coding practices.

RealDiff

MIT 🟢Compares runtime method arguments and return values across Git revisions by running existing Maven or Gradle tests.

RefactorFirst

Apache-2.0 🟢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

LGPL-2.1 🟢Static analysis of bytecode to find potential bugs.

ToolsHref

🟠Online Java code analyzer and JSON-to-Mermaid visualization tool.

Delta Coverage

MIT 🟢Computes code coverage of new and modified code based on a provided diff, supporting JaCoCo and IntelliJ coverage engines.

JaCoCo

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

OpenClover

🟢Measures Java code coverage through source-code instrumentation, with build-tool and IDE integrations.

Supercov

MIT 🟢Measures line, branch, and MC/DC coverage of Java and Kotlin test runs and scores source files for code quality.

google-java-format

🟢Reformats Java source code to follow Google Java Style.

JHarmonizer

🟢Safely reorders Java source code with configurable rules and Palantir Java Format.

Palantir Java Format

Apache-2.0 🟢Formatter based on google-java-format with wider lines and lambda-friendly output.

Spotless

Apache-2.0 🟢A versatile code formatter for Gradle and Maven that enforces multiple styles (including Google and Palantir) across Java and other languages.

Auto

Apache-2.0 🟢Generates factory, service, and value classes.

Avaje HTTP

Apache-2.0 🟢Generates HTTP server adapters and declarative clients, with a lightweight JDK HTTP client.

Bootify

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

Chocotea

Apache-2.0 🔴Generates postman collection, environment and integration tests from java code.

CRUDGen

Apache-2.0 🟠Compile-time annotation processor generating CRUD layers, DTOs, JSON Patch, and custom HTTP endpoints for Spring Boot.

DevOpsForge

MIT 🟢Visual generator for Spring Boot Dockerfiles and Docker Compose configurations.

EasyEntityToDTO

MIT 🟠Annotation processor for automatic DTO and Mapper generation with zero boilerplate.

Geci

Apache-2.0 🟠Discovers files that need generated code, updates automatically and writes to the source with a convenient API.

Immutables

Apache-2.0 🟢Annotation processors to generate simple, safe and consistent value objects.

J2ObjC

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

JHipster

Apache-2.0 🟢Yeoman source code generator for Spring Boot and AngularJS.

Joda-Beans

Apache-2.0 🔴Small framework that adds queryable properties to Java, enhancing JavaBeans.

JPA Buddy

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.

jsonschema2pojo

Apache-2.0 🟠Generates Java types from JSON Schema or example JSON.

JSpecify Package-Info Generator

Apache-2.0 🟠Maven plugin that automatically generates package-info.java files with JSpecify annotations (@NullMarked and @NullUnmarked), helping you manage nullness boundaries in your Java projects without manual boilerplate.

Lombok

🟢Code generator that aims to reduce verbosity.

Record-Builder

Apache-2.0 🟢Companion builder class, withers and templates for Java records.

Spring CRUD Generator

Apache-2.0 🟢Maven plugin for generating Spring Boot CRUD applications from YAML/JSON specifications.

SpringBoot Generator

Browser-based generator producing a Spring Boot CRUD REST API and an optional Angular or React frontend as separately deployable projects, including n-ary association entities. Commercial with a free tier.

Telosys

LGPL-3.0 🟠Java code-generation toolkit with a CLI and model-driven template engine.

ANTLR

BSD-3-Clause 🟠Complex full-featured framework for top-down parsing.

JavaCC

BSD-3-Clause 🔴Parser generator that generates top-down parsers. Allows lexical state switching and permits extended BNF specifications.

JFlex

🔴Lexical analyzer generator.

BoofCV

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

ImageJ

🟢Medical image processing application with an API.

JavaCV

🟢Java interface to OpenCV, FFmpeg, and much more.

avaje config

Apache-2.0 🟢Loads yaml and properties files, supports dynamic configuration, plugins, file-watching and config event listeners.

centraldogma

Apache-2.0 🟢Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.

ClearConfig

Apache-2.0 🟢Type-safe, composable configuration library with a focus on runtime clarity.

config

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

Configurate

Apache-2.0 🟢Configuration library with support for various configuration formats and transformations.

dotenv

🔴Twelve-factor configuration library which uses environment-specific files.

Externalized Properties

Apache-2.0 🟢Simple, lightweight, yet powerful configuration library which supports resolution of properties from external sources such as files, databases, git repositories, and any custom sources, plus an extensible post-processing/conversion mechanism.

Gestalt

Apache-2.0 🟢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.

ini4j

Provides an API for handling Windows' INI files.

KAConf

Apache-2.0 🔴Annotation-based configuration system for Java and Kotlin.

microconfig

Apache-2.0 🔴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.

NightConfig

LGPL-3.0 🟢Configuration library supporting TOML, YAML, HOCON, JSON and in-memory formats.

owner

BSD-3-Clause 🟢Reduces boilerplate of properties.

sealed-env

MIT 🟢Encrypts environment files with a shared Node.js and Java/Spring Boot format plus optional TOTP unsealing.

Choco

BSD-3-Clause 🟢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)

Timefold

Apache-2.0 🟢Flexible solver with Spring/Quarkus support and quickstarts for the Vehicle Routing Problem, Maintenance Scheduling, Employee Shift Scheduling and much more.

FastCSV

MIT 🟢Performance-optimized, dependency-free and RFC 4180 compliant.

jackson-dataformat-csv

Apache-2.0 🟢Jackson extension for reading and writing CSV.

opencsv

Simple CSV parser.

Apache Flink

Apache-2.0 🟢Fast, reliable, large-scale data processing engine.

Apache Storm

Apache-2.0 🟢Realtime computation system.

easy-batch

MIT 🔴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.

Embulk

Apache-2.0 🟠Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.

OpenRefine

BSD-3-Clause 🟢Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.

Scriptella ETL

Apache-2.0 🟢Open-source Java-based ETL and script execution tool for transferring and transforming data between databases, files, and other sources.

Siddhi

Apache-2.0 🟠Cloud native streaming and complex event processing engine.

Smooks

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

Tablesaw

Apache-2.0 🟢Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.

CQEngine Next

Apache-2.0 🟢Provides indexed, SQL-like queries over Java collections.

HashSmith

MIT 🟢Hash map and set implementations using SwissTable-style SWAR/SIMD control-byte probing, optimized for memory efficiency.

Persistent Collection

🔴Persistent and immutable analogue of the Java Collections Framework.

RoaringBitmap

Apache-2.0 🟢Fast and efficient compressed bitmap.

Wormhole4j

Apache-2.0 🟠High-performance sorted map with fast range scans and thread-safe concurrent access, based on the Wormhole index structure.

Actual Schema Gradle Plugin

Apache-2.0 🟢Generates PostgreSQL schema DDL from Liquibase migrations using Testcontainers.

Apache Calcite

Apache-2.0 🟢Dynamic data management framework. It contains many of the pieces that comprise a typical database management system.

Apache Cassandra

Apache-2.0 🟢Distributed wide-column database with linear scalability and fault tolerance.

Apache Doris

Apache-2.0 🟢Distributed SQL database for real-time analytics.

Apache Drill

Apache-2.0 🟢Distributed, schema on-the-fly, ANSI SQL query engine for Big Data exploration.

Apache Phoenix

Apache-2.0 🟢High-performance relational database layer over HBase for low-latency applications.

Apache ShardingSphere

Apache-2.0 🟢Distributed SQL transaction & query engine that allows for data sharding, scaling, encryption, and more on any database.

ArangoDB

Apache-2.0 🟢ArangoDB Java driver.

ArcadeDB

Apache-2.0 🟢Multi-model database supporting graphs, documents, key-value, time series, and vector embeddings with SQL, Cypher, Gremlin, MongoDB, and Redis API compatibility.

Chronicle Map

Apache-2.0 🟢Efficient, in-memory (opt. persisted to disk), off-heap key-value store.

ClickHouse Java

Apache-2.0 🟢Java clients and JDBC driver for ClickHouse.

CosId

Apache-2.0 🟢Universal, flexible, high-performance distributed ID generator.

Debezium

Apache-2.0 🟢Low latency data streaming platform for change data capture.

druid

Apache-2.0 🟢High-performance, column-oriented, distributed data store.

eXist

LGPL-2.1 🟢NoSQL document database and application platform.

FlexyPool

Apache-2.0 🟠Brings metrics and failover strategies to the most common connection pooling solutions.

Flyway

Apache-2.0 🟢Simple database migration tool.

H2

🟢Small SQL database notable for its in-memory functionality.

HikariCP

Apache-2.0 🟠High-performance JDBC connection pool.

HSQLDB

HyperSQL 100% Java database.

JanusGraph

🟢Distributed graph database supporting pluggable storage and indexing backends.

JDBI

Apache-2.0 🟢Convenient abstraction of JDBC.

Jedis

MIT 🟢Java client for Redis with synchronous, asynchronous and cluster APIs.

jetcd

Apache-2.0 🟢Java client for etcd v3.

Jinq

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

jOOQ

🟢Generates typesafe code based on SQL schema.

JQuick SQL

🟢Embeddable, lightweight distributed SQL engine featuring heterogeneous federated query support for unified data access across disparate systems.

Lettuce

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

Liquibase

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

MapDB

Apache-2.0 🟢Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.

MariaDB4j

Apache-2.0 🟢Launcher for MariaDB that requires no installation or external dependencies.

Modality

Apache-2.0 🟢Lightweight ORM with database reverse engineering features.

MongoDB Java Driver

Apache-2.0 🟢Official synchronous, asynchronous and reactive Java drivers for MongoDB.

ObjectBox

Apache-2.0 🟢Embedded object and vector database for Java and Android.

Open J Proxy

Apache-2.0 🟢Type 3 JDBC driver and Layer 7 proxy server for decoupling applications from relational database connection management.

OpenDJ

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

Presto

Apache-2.0 🟢Distributed SQL query engine for large data sources.

Querydsl

Apache-2.0 🟠Typesafe unified queries.

QueryStream

Apache-2.0 🔴Build JPA Criteria queries using a Stream-like API.

QuestDB

Apache-2.0 🟢High-performance SQL database for time series. Supports InfluxDB line protocol, PostgreSQL wire protocol, and REST.

Realm

Apache-2.0 🔴Mobile database to run directly inside phones, tablets or wearables.

Redisson

Apache-2.0 🟢Allows for distributed and scalable data structures on top of a Redis server.

requery

Apache-2.0 🟠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.

SchemaCrawler

🟢Discovers, documents and diagrams relational database schemas from Java, build tools and the command line.

Spring Data Dynamic Query

Apache-2.0 🟠Unified dynamic query interface for Spring Data JPA, MongoDB, and Elasticsearch, enabling advanced JOIN(s), OR logic, scoped conditions, powerful projections and advanced features with zero boilerplate.

Spring Data JPA MongoDB Expressions

Apache-2.0 🟠Allows you to use MongoDB query language to query your relational database.

StarRocks

Apache-2.0 🟢Distributed SQL query engine for real-time analytics and data lakehouses.

Trino

Apache-2.0 🟢Distributed SQL query engine for big data.

Vibur DBCP

Apache-2.0 🔴JDBC connection pool library with advanced performance monitoring capabilities.

Xodus

Apache-2.0 🟢Highly concurrent transactional schema-less and ACID-compliant embedded database.

iCal4j

BSD-3-Clause 🟢Parse and build iCalendar RFC 5545 data models.

Jollyday

Apache-2.0 🟢Determines the holidays for a given year, country/name and eventually state/region.

ThreeTen-Extra

BSD-3-Clause 🟢Additional date-time classes that complement those in JDK 8.

Time4J

LGPL-2.1 🔴Advanced date and time library.

bitcoinj

Apache-2.0 🟢Library for working with the Bitcoin protocol and network.

java-tron

LGPL-3.0 🟢Implementation of the Tron Protocol, whic utilizes blockchains to develop decentralized applications.

web3j

🟢Java and Android library for integrating with Ethereum-compatible blockchains.

CFR

MIT 🟠Java decompiler focused on modern language features.

Fernflower

Apache-2.0 🟢Java decompiler with broad JVM bytecode support.

jadx

Apache-2.0 🟢Dex-to-Java decompiler with command-line and graphical interfaces.

transformer-api

Apache-2.0 🟢Unified API that exposes multiple decompilers through one in-memory transformation interface.

Vineflower

Apache-2.0 🟢Modern maintained fork of Fernflower.

Apache DeltaSpike

Apache-2.0 🟢CDI extension framework.

Avaje Inject

Apache-2.0 🟢Microservice-focused compile-time injection framework without reflection.

Dagger

Apache-2.0 🟢Compile-time injection framework without reflection.

Dimension-DI

Apache-2.0 🟢JSR-330 runtime dependency injection using the JDK Class-File API.

Governator

Apache-2.0 🟠Extensions and utilities that enhance Google Guice.

Guice

Apache-2.0 🟢Lightweight and opinionated framework that completes Dagger.

HK2

🟢Lightweight and dynamic dependency injection framework.

AspectJ

🟠Seamless aspect-oriented programming extension.

Faux Pas

MIT 🔴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.

Ghidra

Apache-2.0 🟢Extensible software reverse-engineering framework with Java APIs and scripting.

HotswapAgent

GPL-2.0 🟢Unlimited runtime class and resource redefinition.

JavaParser

🟢Parse, modify and generate Java code.

Jctx

MIT 🟠Reads a Java project and generates a structured context file so AI tools can understand and help plan the codebase.

JGit

🟢Lightweight, pure Java library implementing the Git version control system.

Manifold

Apache-2.0 🟢Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.

NoException

Apache-2.0 🔴Allows checked exceptions in functional interfaces and converts exceptions to Optional return.

RR4J

GPL-3.0 🔴RR4J is a tool that records java bytecode execution and later allows developers to replay locally.

SneakyThrow

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

Tail

Unlicense 🔴Enable infinite recursion using tail call optimization.

Apache Geode

Apache-2.0 🟢In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.

Apache ZooKeeper

Apache-2.0 🟢Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.

Axon

Apache-2.0 🟢Framework for creating CQRS applications.

Curator Framework

Apache-2.0 🟢High-level API for Apache ZooKeeper.

Dropwizard Circuit Breaker

GPL-2.0 🟠Circuit breaker design pattern for Dropwizard.

Failsafe

Apache-2.0 🟠Simple failure handling with retries and circuit breakers.

Fuse

Apache-2.0 🟢Circuit breaker for Java microservices with zero runtime dependencies and lock-free CAS.

Hazelcast

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

JGroups

Apache-2.0 🟢Toolkit for reliable messaging and cluster creation.

resilience4j

Apache-2.0 🟢Functional fault tolerance library.

ScaleCube Services

Apache-2.0 🟢Embeddable Cluster-Membership library based on SWIM and gossip protocol.

Atomikos

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

Bitronix

Apache-2.0 🟠Simple but complete implementation of the JTA 1.1 API.

Narayana

Apache-2.0 🟢Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards.

Seata

Apache-2.0 🟢Delivers high performance and easy to use distributed transaction services under a microservices architecture.

Artipie

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

Boxfuse

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.

Cloudsmith

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.

IzPack

Apache-2.0 🟢Setup authoring tool for cross-platform deployments.

JavaPackager

GPL-3.0 🟠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.

jDeploy

Apache-2.0 🟢Deploy desktop apps as native Mac, Windows or Linux bundles.

jlink.online

Apache-2.0 🟢Builds optimized runtimes over HTTP.

Nexus

EPL-1.0 🟢Binary management with proxy and caching capabilities.

Nuts

🟢Installs and runs Java applications from Maven repositories, reusing descriptors and provisioning required JDKs.

packr

Apache-2.0 🔴Packs JARs, assets and the JVM for native distribution on Windows, Linux and macOS.

really-executable-jars-maven-plugin

Apache-2.0 🟠Maven plugin for making self-executing JARs.

Apache Tika

Apache-2.0 🟢Detects and extracts text and metadata from a wide range of document formats.

commonmark-java

BSD-2-Clause 🟢Parses and renders CommonMark-compatible Markdown.

documents4j

Apache-2.0 🟠API for document format conversion using third-party converters such as MS Word.

docx4j

🟢Create and manipulate Microsoft Open XML files.

html-to-markdown

MIT 🟢Converts HTML to CommonMark-compatible Markdown through a Java binding.

JQuick Excel

🟢Configures Excel import, export, validation, formulas and charts through a declarative XML DSL.

xberg

MIT 🟢Extracts text, tables and metadata from PDFs, Office documents, images and other formats through a Java binding.

Featureflip Java SDK

Apache-2.0 🟢Java SDK for the Featureflip hosted platform, evaluating flags locally from a streamed rule set with an OpenFeature provider available.

FF4J

Apache-2.0 🟢Feature Flags for Java.

OpenFeature Java SDK

Apache-2.0 🟢Vendor-neutral API for evaluating feature flags in Java applications.

Rollgate Java SDK

MIT 🟢Java SDK for evaluating Rollgate feature flags with real-time configuration updates.

Togglz

Apache-2.0 🟢Implementation of the Feature Toggles pattern.

Unleash Java SDK

Apache-2.0 🟢Java client SDK for the Unleash feature management platform.

Cassandre

GPL-3.0 🔴Trading bot framework.

iban-commons

Apache-2.0 🟢Zero-dependency IBAN and BIC toolkit with allocation-free validation plus parsing and formatting for 127 countries.

Joda-Money

Apache-2.0 🟠Basic currency and money classes and algorithms not provided by the JDK.

nablatensor

Apache-2.0 🟢Adjoint automatic differentiation for quantitative finance; records a valuation once and replays the tape to get a price and every Greek from one reverse sweep, on CPU, SIMD or GPU.

OpenGamma Strata

Apache-2.0 🟢Analytics and market risk library for financial products.

PesaFlow4J

MIT 🟢Dependency-free SDK for the Kenya PesaFlow/eCitizen PaymentAPI, including M-Pesa STK push and webhook signature verification.

Philadelphia

Apache-2.0 🟢Low-latency financial information exchange.

Stripe

MIT 🟢Integration with the Stripe API.

ta4j

🟢Library for technical analysis.

Wickra

Apache-2.0 🟢Technical-analysis library with 514 streaming O(1)-per-tick indicators on a native Rust core, on Maven Central as org.wickra:wickra; more indicators and incremental updates than the pure-Java ta4j.

XChange

MIT 🟢Consistent Java API for market data and trading across cryptocurrency exchanges.

BeanIO

Apache-2.0 🔴Maps flat files of fixed-length or delimited records to and from Java beans using XML or annotation configuration.

fixedformat4j

Apache-2.0 🟢Annotation-driven mapping of fixed-width flat files to and from POJOs and Java records.

Flatpack

Apache-2.0 🟠Parses and writes delimited and fixed-length flat files with optional column-mapping definitions.

Checker Framework

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

Daikon

🟢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.

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)

KeY

🟢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)

OpenJML

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

Fugue

Functional extensions to Guava.

Functional Java

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

jOOλ

Apache-2.0 🔴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.

Packrat

Apache-2.0 🟢Gatherers library for Java Stream API. Gatherers can enhance streams with custom intermediate operations.

Parallel Collectors

Apache-2.0 🟢Stream API Collectors for parallel processing with custom thread pools, designed for I/O-heavy workloads.

protonpack

MIT 🟠Collection of stream utilities.

StreamEx

Apache-2.0 🟢Enhances Java 8 Streams.

Vavr

Apache-2.0 🟢Functional component library that provides persistent data types and functional control structures.

FXGL

MIT 🟢JavaFX Game Development Framework.

input4j

MIT 🟢Lightweight, cross-platform library for gamepad and joystick input handling.

JBox2D

BSD-2-Clause 🔴Port of the renowned C++ 2D physics engine.

jMonkeyEngine

BSD-3-Clause 🟢Game engine for modern 3D development.

libGDX

Apache-2.0 🟢All-round cross-platform, high-level framework.

Litiengine

MIT 🟢AWT-based, lightweight 2D game engine.

LWJGL

BSD-3-Clause 🟢Robust framework that abstracts libraries like OpenGL/CL/AL.

Pathetic

MIT 🟢A highly configurable 3D A* pathfinding library that uses specific optimizations for high performance.

vulkan4j

BSD-3-Clause 🔴Vulkan, OpenGL ES2 and GLFW Memory Allocator bindings.

Apache SIS

Apache-2.0 🟢Library for developing geospatial applications.

ArcGIS Maps SDK for Java

Apache-2.0 🔴JavaFX library for adding mapping and GIS functionality to desktop apps.

Geo

Apache-2.0 🟢GeoHash utilities in Java.

GeoTools

LGPL-2.1 🟢Library that provides tools for geospatial data.

GraphHopper

Apache-2.0 🟢Road-routing engine. Used as a Java library or standalone web service.

H2GIS

LGPL-3.0 🟢Spatial extension of the H2 database.

IP2Location.io Java SDK

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

Jgeohash

Apache-2.0 🔴Library for using the GeoHash algorithm.

JTS

🟢Geometry model and algorithms for manipulating vector geospatial data.

Mapsforge

LGPL-3.0 🟢Map rendering based on OpenStreetMap data.

Open Location Code

Apache-2.0 🟠Encodes geographic coordinates as short, shareable Plus Codes.

Spatial4j

🟢General-purpose spatial/geospatial library.

ControlsFX

BSD-3-Clause 🟢UI controls and components that complement JavaFX.

FlatLaf

Apache-2.0 🟢Modern Swing Look and Feel with Darcula and IntelliJ themes.

JavaFX

GPL-2.0 🟢Successor of Swing.

Scene Builder

🟠Visual layout tool for JavaFX applications.

Sierra

Apache-2.0 🟢Lightwieght declarative DSL for rapid development of Swing applications.

SnapKit

🟢Modern Java UI library for both desktop and web.

SWT

EPL-2.0 🟢Graphical widget toolkit.

Agrona

Apache-2.0 🟢Data structures and utility methods that are common in high-performance applications.

Disruptor

Apache-2.0 🔴Inter-thread messaging library.

Eclipse Collections

🟢Collections framework inspired by Smalltalk.

fastutil

Apache-2.0 🟢Fast and compact type-specific collections.

Hollow

Apache-2.0 🟢High-performance in-memory datasets distributed from a single producer to many consumers.

HPPC

Apache-2.0 🟢Primitive collections.

JCTools

Apache-2.0 🟢Concurrency tools currently missing from the JDK.

TransmittableThreadLocal

Apache-2.0 🟠Propagates thread-local context across thread pools and asynchronous execution.

Apache HttpComponents

🟢Toolset of low-level Java components focused on HTTP and related protocols.

Async Http Client

Apache-2.0 🟢Asynchronous HTTP and WebSocket client library.

Feign

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

Google HTTP Client

Apache-2.0 🟢Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf.

JQuickCurl

Apache-2.0 🟢Executes HTTP requests from cURL syntax through annotations, XML configuration and dynamic proxy clients.

methanol

MIT 🟠HTTP client extensions library.

OkHttp

Apache-2.0 🟢HTTP client for the JVM, Android and GraalVM.

Retrofit

Apache-2.0 🟢Typesafe REST client.

Ribbon

Apache-2.0 🟠Client-side IPC library that is battle-tested in the cloud.

Riptide

MIT 🟢Client-side response routing for Spring's RestTemplate.

unirest-java

MIT 🟢Simplified, lightweight HTTP client library.

Eclipse Java IDE

EPL-2.0 🟢Extensible Java IDE assembled from the Eclipse Platform, JDT and PDE.

Explyt

🟢AI coding agent for JetBrains IDEs that uses IDE indexes, refactorings, test runners, static analysis and debugging for Java and Kotlin projects.

IntelliJ IDEA

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

jGRASP

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

NetBeans

Apache-2.0 🟢Provides integration for several Java SE and EE features, from database access to HTML5.

SnapCode

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

Visual Studio Code Java

🟢Extension suite providing Java language support, debugging, testing, Maven, Gradle and project management in Visual Studio Code.

Barcode-Lib4J

Apache-2.0 🟢Generates QR Code, DataMatrix, and other 1D/2D barcodes as vector (PDF, EPS, SVG) and raster (PNG, BMP, JPG) images with DPI awareness, high precision, and CMYK color model support.

Glide

🟢Image loading and caching library for Android focused on smooth scrolling.

image-comparison

Apache-2.0 🟢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.

Imgscalr

Apache-2.0 🔴Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.

scrimage

Apache-2.0 🟢Immutable, functional, and performant JVM library for manipulation of images.

Tess4J

Apache-2.0 🟢JNA wrapper for Tesseract OCR API.

Thumbnailator

MIT 🟠High-quality thumbnail generation library.

TwelveMonkeys

BSD-3-Clause 🟢Collection of plugins that extend the number of supported image file formats.

vips-ffm

Apache-2.0 🟢Comprehensive bindings for libvips, using Java's "Foreign Function & Memory" API.

webcam-capture

MIT 🟠Library for using built-in and external webcams directly in Java.

ZXing

Apache-2.0 🟢Multi-format 1D/2D barcode image processing library.

ClassGraph

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

jOOR

Apache-2.0 🔴jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package.

Objenesis

Apache-2.0 🟢Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions.

ReflectASM

BSD-3-Clause 🔴ReflectASM is a very small Java library that provides high performance reflection by using code generation.

TypeTools

Apache-2.0 🔴Tools for resolving generic types.

db-scheduler

Apache-2.0 🟢Persistent and cluster-friendly scheduler.

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

Apache-2.0 🟢Feature-rich, open source job scheduling library that can be integrated within virtually any Java application.

shedlock

Apache-2.0 🟢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.

Sundial

Apache-2.0 🟠Lightweight framework to simply define jobs, define triggers and start the scheduler.

Wisp

Apache-2.0 🟠Simple library with minimal footprint and straightforward API.

XXL-JOB

GPL-3.0 🟢Distributed task scheduling platform with centralized administration and execution monitoring.

Avaje Jsonb

Apache-2.0 🟢Reflection-free Json binding via source code generation with Jackson-like annotations.

DSL-JSON

BSD-3-Clause 🟢JSON library with advanced compile time databinding.

Fastjson2

Apache-2.0 🟢High-performance JSON parser, serializer and object mapper.

Gson

Apache-2.0 🟢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.

jackson-modules-java8

Apache-2.0 🟢Set of Jackson modules for Java 8 datatypes and features.

Jolt

Apache-2.0 🟢JSON to JSON transformation tool.

JSON-io

Apache-2.0 🟢Convert Java to JSON/TOON and back. Supports complex object graphs, cyclic references, and TOON format for 40-50% LLM token savings.

JsonPath

Apache-2.0 🟠Extract data from JSON using XPATH-like syntax.

JsonSurfer

MIT 🔴Streaming JsonPath processor dedicated to processing big and complicated JSON data.

Moshi

Apache-2.0 🟢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.

Corretto

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

Dragonwell8

GPL-2.0 🟢Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.

Eclipse Temurin

Apache-2.0 🟢OpenJDK distribution from the Eclipse Adoptium project.

Graal

🟢Polyglot embeddable JVM. (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)

Microsoft JDK

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

Open JDK

GPL-2.0 🟢Open JDK community home.

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.

RedHat Open JDK

RedHat's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)

SAP Machine

GPL-2.0 🟢SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork.

Zulu

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

Apache Log4j 2

Apache-2.0 🟢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.

Flogger

Apache-2.0 🟢Flogger is a fluent logging API for Java. It supports a wide variety of features, and has many benefits over existing logging APIs.

Graylog

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

Kibana

🟢Analyzes and visualizes log files. Some features require payment.

Logback

🟢Robust logging library with interesting configuration options via Groovy.

Logbook

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

Logstash

🟢Tool for managing log files.

SLF4J

MIT 🟢Abstraction layer/simple logging facade.

tinylog

Apache-2.0 🟢Lightweight logging framework with static logger class.

Apache Mahout

Apache-2.0 🟢Scalable algorithms focused on collaborative filtering, clustering and classification.

DatumBox

Apache-2.0 🔴Provides several algorithms and pre-trained models for natural language processing.

Deeplearning4j

Apache-2.0 🟢Distributed and multi-threaded deep learning library.

DJL

Apache-2.0 🟢High-level and engine-agnostic framework for deep learning.

H2O

Apache-2.0 🟢Analytics engine for statistics over big data.

Intelligent java

Apache-2.0 🔴Seamlessly integrate with remote deep learning and language models programmatically.

JSAT

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

LIBSVM

BSD-3-Clause 🟠Support vector machine library with Java bindings and command-line tools.

Neureka

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

oj! Algorithms

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

sklearn-java

Apache-2.0 🟢Implements scikit-learn-style machine learning algorithms in pure Java.

Smile

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

Tribuo

Apache-2.0 🟠Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.

Weka

Collection of algorithms for data mining tasks ranging from pre-processing to visualization.

Aeron

Apache-2.0 🟢Efficient, reliable, unicast and multicast message transport.

Apache ActiveMQ

Apache-2.0 🟢Message broker that implements JMS and converts synchronous to asynchronous communication.

Apache Camel

Apache-2.0 🟢Glues together different transport APIs via Enterprise Integration Patterns.

Apache Kafka

Apache-2.0 🟢High-throughput distributed messaging system.

Apache Pulsar

Apache-2.0 🟢Distributed pub/sub-messaging system.

Apache Qpid for Java

Apache-2.0 🟢Java messaging clients and brokers implementing AMQP.

Apache RocketMQ

Apache-2.0 🟢Fast, reliable, and scalable distributed messaging platform.

AutoMQ

Apache-2.0 🟢AutoMQ is a cloud-native, serverless reinvented Kafka that is easily scalable, manage-less and cost-effective.

CloudEvents Java SDK

Apache-2.0 🟢Java SDK for creating, serializing and transporting CloudEvents.

Emissary

Apache-2.0 🟢Simple, lightweight, yet FAST messaging library for decoupling messages (requests and events) and message handlers.

Hermes

🟢Fast and reliable message broker built on top of Kafka.

HiveMQ MQTT Client

Apache-2.0 🟢Reactive and blocking Java client for MQTT 3.1.1 and MQTT 5.

JeroMQ

MPL-2.0 🟠Implementation of ZeroMQ.

NATS client

Apache-2.0 🟢NATS client.

Pushy

MIT 🟢Java library for sending Apple Push Notification service messages.

RabbitMQ Java client

🟢RabbitMQ client.

Simple Java Mail

Apache-2.0 🟢Mailing with a clean and fluent API.

Smack

Apache-2.0 🟢Cross-platform XMPP client library.

Svix

MIT 🟢Library for the Svix API to send webhooks and verify signatures.

Armeria

Apache-2.0 🟢Asynchronous RPC/REST client/server library built on top of Java 8, Netty, HTTP/2, Thrift and gRPC.

Eureka

Apache-2.0 🟢REST-based service registry for resilient load balancing and failover.

gRPC Spring

Apache-2.0 🟢Spring Boot integration for building gRPC clients and servers.

Helidon

Apache-2.0 🟢Two-style approach for writing microservices: Functional-reactive and as an implementation of MicroProfile.

Micronaut

Apache-2.0 🟢Modern full-stack framework with focus on modularity, minimal memory footprint and startup time.

Nacos

Apache-2.0 🟢Dynamic service discovery, configuration and service management platform for building cloud native applications.

Quarkus

Apache-2.0 🟢Kubernetes stack tailored for the HotSpot and Graal VM.

Sentinel

Apache-2.0 🟠Flow control component enabling reliability, resilience and monitoring for microservices.

JBake

MIT 🟠Static website generator.

JObfuscator

Source code obfuscator.

yGuard

MIT 🟠Obfuscation via renaming and shrinking.

Codename One

🟢Cross-platform Java framework for native mobile, desktop, web and watch apps. (GPL-2.0-only WITH Classpath-exception-2.0)

Gluon Substrate

GPL-2.0 🟠Builds native JavaFX applications for desktop, mobile and embedded targets.

MobileUI

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

Multi-OS Engine

Apache-2.0 🟢Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.

Apitally

MIT 🟢Simple, privacy-focused API monitoring, analytics and request logging for Spring Boot apps.

Arthas

Apache-2.0 🟢Allows to troubleshoot production issues for applications without modifying code or restarting servers.

Automon

Apache-2.0 🔴Combines the power of AOP with monitoring and/or logging tools.

Boot Usage Spring Boot Starter

Apache-2.0 🟢Spring Boot Actuator extension providing application startup and runtime metrics including JVM uptime, memory usage, and CPU load.

BTrace

Apache-2.0 🟢Dynamic tracing and diagnostics for running JVM applications without restarts.

Datadog

Apache-2.0 🟢Modern monitoring & analytics.

Dropwizard Metrics

Apache-2.0 🟢Expose metrics via JMX or HTTP and send them to a database.

Glowroot

Apache-2.0 🟢Open-source Java APM.

HertzBeat

Apache-2.0 🟢Real-time monitoring system with custom-monitor and agentless.

hippo4j

Apache-2.0 🟠Dynamic and observable thread pool framework.

inspectIT Ocelot

Apache-2.0 🟠Java agent that collects application performance, tracing and behavioral data.

JavaMelody

Apache-2.0 🟢Performance monitoring and profiling.

Jolokia

Apache-2.0 🟢JMX over REST.

Micrometer

Apache-2.0 🟢Vendor-neutral metrics/observability facade for the most popular metrics/observability libraries.

Micrometer Tracing

Apache-2.0 🟢Vendor-neutral distributed tracing facade for the most popular tracer libraries.

OpenTelemetry

Apache-2.0 🟢Instrument, generate, collect, and export telemetry data to help you analyze your software’s performance and behavior.

Pinpoint

Apache-2.0 🟢Open-source APM tool.

Prometheus

Apache-2.0 🟢Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.

Sentry

MIT 🟢Integration with Sentry, an application error tracking and performance analysis platform.

SPM

Apache-2.0 🟢Performance monitor with distributing transaction tracing for JVM apps.

StatLite

MIT 🟢Self-hosted monitoring dashboard with direct Spring Boot Actuator/Micrometer and Quarkus integrations, SQLite storage, and no Prometheus or Grafana required.

zipkin

Apache-2.0 🟢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++.

JCuda

MIT 🔴JCuda offers Java bindings for CUDA and CUDA-related libraries.

JNA

🟢Work with native libraries without writing JNI. Also provides interfaces to common system libraries.

JNR

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

native-lib-loader

🔴Native library loader for extracting and loading native libraries from Java.

Apache OpenNLP

Apache-2.0 🟢Toolkit for machine-learning-based natural language processing.

CoreNLP

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

DKPro

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

Hypherator

MIT 🔴Java hyphenation library with iterator-like interface. Can be used out-of-the box - dictionaries for multiple languages are bundled in.

LingPipe

Toolkit for tasks ranging from POS tagging to sentiment analysis.

AISmessages

🟢Decodes NMEA-armoured AIS messages for maritime navigation and safety systems with ITU-R M.1371 support and no runtime dependencies. (CC-BY-NC-SA-4.0)

Apache MINA sshd

Apache-2.0 🟢Java implementation of SSH clients, servers, SFTP and SCP.

Atmosphere

Apache-2.0 🟢Real-time transport framework supporting WebSocket, SSE, gRPC and WebTransport.

Commons-networking

Apache-2.0 🔴Client for server-sent events (SSE).

dnsjava

BSD-3-Clause 🟢Java implementation of the DNS protocol.

Drift

Apache-2.0 🟢Easy-to-use, annotation-based library for creating Thrift clients and serializable types.

Dubbo

Apache-2.0 🟢High-performance RPC framework.

Fluency

Apache-2.0 🟢High throughput data ingestion logger to Fluentd and Fluent Bit.

Grizzly

🟢NIO framework. Used as a network layer in Glassfish.

gRPC-java

Apache-2.0 🟢RPC framework based on protobuf and HTTP/2.

java-ngrok

MIT 🟢Java wrapper for ngrok; programmatic tunnels for ingress, webhooks, demos, and APIs.

Java-WebSocket

MIT 🟠Lightweight WebSocket client and server implementation.

MINA

Apache-2.0 🟢Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.

MinimalFTP

Apache-2.0 🔴Lightweight, small and customizable FTP server.

Netty

Apache-2.0 🟢Framework for building high-performance network applications.

ServiceTalk

Apache-2.0 🟢Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.

Socket.IO Client Java

🔴Java client for Socket.IO servers.

sshj

Apache-2.0 🟢Programmatically use SSH, SCP or SFTP.

TLS Channel

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

Undertow

Apache-2.0 🟢Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly.

urnlib

GPL-3.0 🟠Represent, parse and encode URNs, as in RFC 2141.

WebSocket4Java

MIT 🟢WebSocket framework based on JDK NIO and virtual threads, with zero third-party dependencies at runtime.

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

Apache-2.0 🟢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

Apache-2.0 🟢Provides simple and fast data access.

EclipseLink

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

Ekbatan

Apache-2.0 🟢Modern Java persistence framework for event-driven systems, with an ergonomic outbox that commits state and events in one transaction.

Hibernate

Apache-2.0 🟢Robust and widely used, with an active community.

MyBatis

Apache-2.0 🟢Couples objects with stored procedures or SQL statements.

mybatis-dynamic

🟠Code-first dynamic ORM for MyBatis with runtime schema modification.

MyBatis-Plus

Apache-2.0 🟢A powerful enhanced toolkit of MyBatis for simplifying development.

ObjectiveSql

Apache-2.0 🔴ActiveRecord ORM for rapid development and convention over configuration.

Permazen

Apache-2.0 🟠Language-natural persistence layer.

SimpleFlatMapper

MIT 🔴Simple database and CSV mapper.

Ujorm

Apache-2.0 🟢Maps rows to JavaBeans or Java records with no third-party runtime dependencies, deliberately omitting lazy loading, 1:M collections and transaction management.

AWS Elastic Beanstalk

AWS-based, with support for Tomcat and Jetty.

AWS Lambda

Serverless computation.

Google Cloud

Google's cloud infrastructure.

Heroku

Abstract computing environments.

Microsoft Azure

Microsoft's cloud infrastructure.

OpenShift

Provides additionally an on-premise solution.

Apache FOP

Apache-2.0 🟢Creates PDFs from XSL-FO.

Apache PDFBox

Apache-2.0 🟢Toolbox for creating and manipulating PDFs.

DynamicReports

LGPL-3.0 🟠Simplifies JasperReports.

Eclipse BIRT

EPL-2.0 🟢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)

GraphCompose

MIT 🟢Declarative engine for structured business PDFs with semantic layout, atomic pagination, theme tokens, and native vector charts.

iText

🟢Creates PDF files programmatically.

JasperReports

LGPL-3.0 🟢Complex reporting engine.

jquick-pdf

🟢Generates PDFs from HTML-like templates and ECharts-style charts using iText 7, without a browser dependency.

Nostrum Dynamic Jasper

LGPL-3.0 🟠Provides dynamic report layouts on top of JasperReports.

Open HTML to PDF

🟢Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.

OpenDataLoader PDF

Apache-2.0 🟢Parses PDFs into structured Markdown, JSON and HTML through a Java API and command line.

OpenPDF

🟢Open-source iText fork. (LGPL-3.0-only & MPL-2.0)

Argus

MIT 🟢JVM diagnostics CLI for jcmd, JFR, async-profiler, heap analysis and machine-readable health verdicts.

async-profiler

Apache-2.0 🟢Low-overhead sampling profiler for CPU, allocation and lock analysis on the JVM.

fastThread

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

GCeasy

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

Heap Seance

Apache-2.0 🟠Memory leak diagnostics that orchestrates jcmd, jmap, jstat, JFR, Eclipse MAT, and async-profiler into a structured investigation workflow with confidence-based verdicts.

JDK Mission Control

🟢Profiling and diagnostics suite for JVM applications using Java Flight Recorder.

jHiccup

🟠Logs and records platform JVM stalls.

JITWatch

🟢Analyze the JIT compiler optimisations made by the HotSpot JVM.

JMH

GPL-2.0 🟢Harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM.

JVM Hotpath

MIT 🟠Java agent for line-level execution frequency analysis to identify algorithmic bottlenecks.

LatencyUtils

🔴Utilities for latency measurement and reporting.

ThreadMine

Web-based analyzer for JVM thread dumps from HotSpot, OpenJ9, Zing and GraalVM that detects deadlocks, pool exhaustion and virtual thread pinning. Free tier with paid plans.

ThreadMine Anonymizer

MIT 🟢Local CLI that replaces an application's own package, class, method and thread names in JVM thread dumps with keyed tokens, keeps JDK and framework frames intact so the dump stays analyzable, and unmasks the analyzer's report afterwards.

BCEL

Apache-2.0 🟢Byte Code Engineering Library - analyze, create, and manipulate Java class files.

BeanUtils

Apache-2.0 🟢Easy-to-use wrappers around the Java reflection and introspection APIs.

BSF

Apache-2.0 🟢Bean Scripting Framework - interface to scripting languages, including JSR-223.

ClassScan

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

CLI

Apache-2.0 🟢Command-line arguments parser.

CLI2

Redesign of Commons CLI.

Codec

Apache-2.0 🟢General encoding/decoding algorithms, e.g. phonetic, base64 or URL.

Collections

Apache-2.0 🟢Extends or augments the Java Collections Framework.

Compress

Apache-2.0 🟢Defines an API for working with tar, zip and bzip2 files.

Configuration

Apache-2.0 🟢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

Apache-2.0 🟢Component for reading and writing comma separated value files.

Daemon

Apache-2.0 🟢Alternative invocation mechanism for unix-daemon-like java code.

DBCP

Apache-2.0 🟢Database connection pooling services.

DbUtils

Apache-2.0 🟢JDBC helper library.

Digester

Apache-2.0 🟢XML-to-Java-object mapping utility.

Email

Apache-2.0 🟢Library for sending e-mail from Java.

Exec

Apache-2.0 🟢API for dealing with external process execution and environment management in Java.

FileUpload

Apache-2.0 🟢File upload capability for your servlets and web applications.

Finder

Java library inspired by the UNIX find command.

Flatfile

Java library for working with flat data structures.

Graph

Apache-2.0 🟢General purpose graph APIs and algorithms.

I18n

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

Id

Id is a component used to generate identifiers.

Imaging

Apache-2.0 🟢Image library.

IO

Apache-2.0 🟢Collection of I/O utilities.

Javaflow

Continuation implementation to capture the state of the application.

JCI

Apache-2.0 🟢Java Compiler Interface.

JCS

Apache-2.0 🟢Java Caching System.

Jelly

Apache-2.0 🟢XML based scripting and processing engine.

Jexl

Apache-2.0 🟢Expression language which extends the Expression Language of the JSTL.

JNet

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

JXPath

Apache-2.0 🟢Utilities for manipulating Java Beans using the XPath syntax.

Lang

Apache-2.0 🟢Provides extra functionality for classes in java.lang.

Logging

Apache-2.0 🟢Wrapper around a variety of logging API implementations.

Math

Apache-2.0 🟢Lightweight, self-contained mathematics and statistics components.

Monitoring

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

Nabla

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

Net

Apache-2.0 🟢Collection of network utilities and protocol implementations.

OpenPGP

Interface to signing and verifying data using OpenPGP.

Performance

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

Pipeline

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

Pool

Apache-2.0 🟢Generic object pooling component.

RDF

Apache-2.0 🟢Common implementation of RDF 1.1 that could be implemented by systems on the JVM.

RNG

Apache-2.0 🟢Commons Rng provides implementations of pseudo-random numbers generators.

SCXML

Apache-2.0 🟢Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.

Validator

Apache-2.0 🟢Framework to define validators and validation rules in an xml file.

VFS

Apache-2.0 🟢Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.

Weaver

Apache-2.0 🟢Provides an easy way to enhance (weave) compiled bytecode.

CUBA Platform

Apache-2.0 🟢High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.

Light-4J

Apache-2.0 🟢Fast, lightweight and productive microservices framework with built-in security.

Spring Framework

Apache-2.0 🟢Comprehensive application framework for building Java applications.

ch.vorburger.exec

Apache-2.0 🟢Convenient API around Apache Commons Exec.

zt-exec

Apache-2.0 🟢Provides a unified API to Apache Commons Exec and ProcessBuilder.

zt-process-killer

Apache-2.0 🟢Stops processes started from Java or the system processes via PID.

LittleProxy

Apache-2.0 🟢High performance HTTP proxy atop Netty's event-based networking library.

Membrane Service Proxy

Apache-2.0 🟢Open-source, reverse-proxy framework.

OpenIG

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

Spring Cloud Gateway

Apache-2.0 🟢API gateway built on Spring Framework and Spring Boot.

Zuul

Apache-2.0 🟢Gateway service that provides dynamic routing, monitoring, resiliency, security, and more.

Akka

🟢Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.

Reactive Streams

MIT-0 🔴Provides a standard for asynchronous stream processing with non-blocking backpressure.

Reactor

Apache-2.0 🟢A framework for building non-blocking applications on the JVM, providing support for reactive programming.

RxJava

Apache-2.0 🟢Allows for composing asynchronous and event-based programs using observable sequences.

vert.x

🟢Polyglot event-driven application framework.

dregex

BSD-2-Clause 🟠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.

JavaVerbalExpressions

MIT 🟢Library that helps with constructing difficult regular expressions.

RE2/J

🟠Java port of RE2 providing linear-time regular expression matching.

Sift

Apache-2.0 🟢Type-safe, AST-based Regex Builder focused on readability and ReDoS prevention.

Dropwizard

Apache-2.0 🟢Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.

Elide

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

hate

MIT 🔴Builds hypermedia-friendly objects according to HAL specification.

Jersey

🟢JAX-RS reference implementation.

OfficeFloor

Apache-2.0 🟢Spring Boot add-on that adds explicit function orchestration to REST endpoints, with each endpoint's steps, branches and error flows in one YAML file whose directory path maps to the URL.

openapi-generator

Apache-2.0 🟢Allows generation of API client libraries, SDKs, server stubs, documentation and configuration automatically given an OpenAPI Spec.

RESTEasy

Apache-2.0 🟢Fully certified and portable implementation of the JAX-RS specification.

RestExpress

Apache-2.0 🟠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.

Spark

Apache-2.0 🔴Sinatra inspired framework.

Spring HATEOAS

Apache-2.0 🟢Standalone and Spring support for building hypermedia-based APIs using HAL, HAL FORMS, Collection+JSON, ALPS and UBER.

springdoc-openapi

Apache-2.0 🟢Automates the generation of API documentation using Spring Boot projects.

Swagger Java

Apache-2.0 🟢Java libraries for generating, parsing and serving OpenAPI definitions.

BioJava

LGPL-2.1 🟢Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.

Chart-FX

LGPL-3.0 🟠Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets.

DataMelt

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

Erdos

MIT 🔴Modular, light and easy graph framework for theoretic algorithms.

Gephi

GPL-3.0 🟢Cross-platform for visualizing and manipulating large graph networks.

JFreeChart

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

JGraphT

EPL-2.0 🟢Graph library that provides mathematical graph-theory objects and algorithms.

jSciPy

MIT 🟠jSciPy is a Java library designed for scientific computing, offering functionalities inspired by popular scientific computing libraries. It currently provides modules for signal processing, including Butterworth filters, peak finding algorithms, and an RK4 solver for ordinary differential…

LogicNG

Apache-2.0 🟢Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas.

Mines Java Toolkit

Apache-2.0 🔴Library for geophysical scientific computation, visualization and digital signal analysis.

Orekit

Apache-2.0 🟢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

GPL-3.0 🔴Generates a wide variety of 3D charts that can be displayed with Swing and JavaFX or exported to PDF, SVG, PNG and JPEG.

XChart

Apache-2.0 🟢Light-weight library for plotting data. Many customizable chart types are available.

JBang

MIT 🟢JBang makes it easy to use Java for scripting. It lets you use a single file for code and dependency management and allows you to run it directly.

JPad

Snippet runner.

JQuick Java

🟢Java-like scripting language for dynamic rule engines with XML orchestration and Java interoperability.

Apache Lucene

Apache-2.0 🟢High-performance, full-featured, cross-platform, text search engine library.

Apache Solr

Apache-2.0 🟢Enterprise search engine optimized for high-volume traffic.

Elasticsearch

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

Elasticsearch Java Client

Apache-2.0 🟢Official typed Java client for Elasticsearch.

OpenSearch

Apache-2.0 🟢Distributed search and analytics engine derived from Elasticsearch.

Viglet Turing ES

Apache-2.0 🟢Self-hosted enterprise search platform with faceted, semantic and hybrid search, RAG, AI agents and pluggable Solr, Elasticsearch or Lucene backends.

Apache Shiro

Apache-2.0 🟢Performs authentication, authorization, cryptography and session management.

Ayza

Apache-2.0 🟢High-level SSL configuration builder for configuring HTTP clients and servers with SSL/TLS.

Bashkit4j

MIT 🟢Sandboxed bash interpreter for running untrusted scripts in-process: in-memory filesystem, opt-in allowlisted host mounts, network denied by default.

Bouncy Castle

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

Certificate Ripper

Apache-2.0 🟢CLI tool and library for extracting and exporting server certificates from HTTPS endpoints.

Cryptomator

GPL-3.0 🟢Multiplatform, transparent, client-side encryption of files in the cloud.

Dependency-Track

Apache-2.0 🟢Software composition analysis platform for identifying supply-chain risk.

Jasypt Spring Boot

MIT 🟠Integrates encrypted properties with Spring Boot applications.

jjwt

Apache-2.0 🟢JSON web token for Java and Android.

Jwks RSA

MIT 🟢JSON Web Key Set parser.

jwt-java

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

Keycloak

Apache-2.0 🟢Integrated SSO and IDM for browser apps and RESTful web services.

MOSS

🟢Cryptographic signing for AI agents using ML-DSA-44 post-quantum signatures, creating audit trails for attribution and compliance.

Nbvcxz

MIT 🟢Advanced password strength estimation.

OpenAM

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

OTP-Java

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

OWASP Dependency-Check

Apache-2.0 🟢Detects publicly disclosed vulnerabilities contained within a project's dependencies.

pac4j

Apache-2.0 🟢Security engine.

Passay

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

Password4j

Apache-2.0 🟠User-friendly cryptographic library that supports Argon2, Bcrypt, Scrypt, PBKDF2 and various other cryptographic hash functions.

ScribeJava

MIT 🟠OAuth client library supporting OAuth 1.0a, OAuth 2.0 and numerous providers.

SecurityBuilder

Apache-2.0 🔴Fluent Builder API for JCA and JSSE classes and especially X.509 certificates.

Spring Security

Apache-2.0 🟢Authentication and access-control framework with OAuth 2.1 and OpenID Connect authorization server support.

Themis

Apache-2.0 🟠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

Apache-2.0 🟢Provides a simple and misuse-proof API for common cryptographic tasks.

Topaz

Apache-2.0 🟢Fine-grained authorization for applications with support for RBAC, ABAC, and ReBAC.

WebAuthn4J

Apache-2.0 🟢Server-side WebAuthn and passkey verification library.

Apache Avro

Apache-2.0 🟢Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.

Apache Fory

Apache-2.0 🟢High-performance object graph serialization framework with JIT and zero-copy support.

Apache Orc

Apache-2.0 🟢Fast and efficient columnar storage format for Hadoop-based workloads.

Apache Parquet

Apache-2.0 🟢Columnar storage format based on assembly algorithms from Google's paper on Dremel.

Apache Thrift

Apache-2.0 🟢Data interchange format that originated at Facebook.

FlatBuffers

Apache-2.0 🟢Memory-efficient serialization library that can access serialized data without unpacking and parsing it.

Kryo

BSD-3-Clause 🟢Fast and efficient object graph serialization framework.

MessagePack

Apache-2.0 🟢Efficient binary serialization format.

Protobuf

🟢Google's data interchange format.

SBE

Apache-2.0 🟢Simple Binary Encoding, one of the fastest message formats around.

Wire

Apache-2.0 🟢Clean, lightweight protocol buffers.

XMLBeam

Apache-2.0 🔴Processes XML by using annotations or XPath within code.

Apache Tomcat

Apache-2.0 🟢Robust, all-round server for Servlet and JSP.

Apache TomEE

Apache-2.0 🟢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

Apache-2.0 🟢Formerly known as JBoss and developed by Red Hat with extensive Java EE support.

Apache Fesod

Apache-2.0 🟢Memory-efficient library for reading and writing large spreadsheet files.

Apache POI

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

fastexcel

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

jackson-dataformat-spreadsheet

Apache-2.0 🟢Jackson dataformat module for reading and writing Excel (XLSX/XLS) as POJOs via ObjectMapper.

Jxls

Apache-2.0 🟢Generates Excel reports from spreadsheet templates.

Sheetz

Apache-2.0 🟢Reads and writes Excel, CSV and ODS files with annotation mapping, streaming, styling and validation.

zerocell

Apache-2.0 🔴Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead.

Freemarker

Apache-2.0 🟢Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.

Handlebars.java

🟢Logicless and semantic Mustache templates.

Jamal

Apache-2.0 🔴Extendable template engine embedded into Maven/JavaDoc, supporting multiple extensions (Groovy, Ruby, JavaScript, JShell, PlantUml) with support for snippet handling.

jstachio

BSD-3-Clause 🔴Typesafe Mustache templating engine.

jte

Apache-2.0 🟢Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.

Pebble

BSD-3-Clause 🟢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.

Thymeleaf

Apache-2.0 🟠Aims to be a substitute for JSP and works for XML files.

Cucumber

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

J8Spec

MIT 🔴Follows a Jasmine-like syntax.

JBehave

BSD-3-Clause 🟠Extensively configurable framework that describes stories.

JGiven

Apache-2.0 🟢Provides a fluent API which allows for simpler composition.

Kensa

Apache-2.0 🟢Code-first BDD framework for Java and Kotlin that generates interactive HTML reports and sequence diagrams from test code.

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.

AutoParams

MIT 🟠Supports generating test data or combining scenarios for parameterized tests.

Datafaker

Apache-2.0 🟢Modern fake data generator forked from Java Faker.

Instancio

Apache-2.0 🟢Automates data setup in unit tests by generating fully-populated, reproducible objects. Includes JUnit 5 extension.

jFairy

Apache-2.0 🟢Fake data generator.

JMock

Apache-2.0 🟢JMock is a high-performance data generation and simulation component library implemented in Java.

Randomized Testing

Apache-2.0 🟢JUnit test runner and plugins for running JUnit tests with pseudo-randomness.

BitDive Java Agent

🟠Java agent that captures runtime traces, SQL queries and HTTP payloads for BitDive testing.

jqwik

EPL-2.0 🟢Engine for property-based testing built on JUnit 5.

JUnit

EPL-2.0 🟢Common testing framework.

PIT

Apache-2.0 🟢Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.

Robolectric

🟢Runs Android tests on the JVM without an emulator or device.

selenium

Apache-2.0 🟢Browser automation framework and ecosystem.

Selenium Boot

🟢Zero-boilerplate Selenium + TestNG framework with auto driver management, smart retry, self-healing locators, AI failure analysis, and a built-in HTML report.

Arquillian

Apache-2.0 🟢Integration and functional testing platform for Java EE containers.

cdi-test

Apache-2.0 🟢JUnit extension for easy and efficient testing of CDI components.

Citrus

Apache-2.0 🟢Integration testing framework that focuses on both client- and server-side messaging.

GreenMail

Apache-2.0 🟢In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL.

Hoverfly Java

Apache-2.0 🟠Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services.

Karate

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

kubetest4j

Apache-2.0 🟢Declarative, annotation-based testing library for Kubernetes and OpenShift with automatic resource lifecycle management, multi-cluster support, and integrated log collection.

Pact JVM

Apache-2.0 🟢Consumer-driven contract testing.

REST Assured

Apache-2.0 🟢DSL for easy testing of REST/HTTP services.

Testcontainers

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

WebTau

Apache-2.0 🟠Test across REST-API, Graph QL, Browser, Database, CLI and Business Logic with consistent set of matchers and concepts.

weld-testing

Apache-2.0 🟢Set of test framework extensions (JUnit 4, JUnit 5, Spock) to enhance the testing of CDI components via Weld. Supports Weld 5.

AssertJ

Apache-2.0 🟢Fluent assertions that improve readability.

JsonUnit

Apache-2.0 🟢Library that simplifies JSON comparison in tests.

Truth

Apache-2.0 🟢Google's fluent assertion and proposition framework.

XMLUnit

Apache-2.0 🟢Simplifies testing for XML output.

Awaitility

Apache-2.0 🟠DSL for synchronizing asynchronous operations.

ConcurrentUnit

Apache-2.0 🔴Toolkit for testing multi-threaded and asynchronous applications.

ConsoleCaptor

Apache-2.0 🟢Captures console output for unit testing purposes.

junit-dataprovider

Apache-2.0 🟠TestNG-like data provider/runner for JUnit.

junit-pioneer

EPL-2.0 🟢JUnit 5 extension pack, pushing the frontiers on Jupiter.

log-capture

MIT 🟠Captures log entries and provides assertions for unit and integration testing.

LogCaptor

Apache-2.0 🟢Captures log entries for unit testing purposes.

Qualflare TestNG

Apache-2.0 🟢TestNG listener that keeps every retry attempt and reports timeouts and configuration failures as distinct statuses.

Selfie

Apache-2.0 🟢Snapshot testing (inline and on disk).

skipper-java

MIT 🟠Real-time test execution control via Google Spreadsheet, enabling instant toggle without code changes.

Stebz

MIT 🟢Multi-approach framework for test steps managing.

test-watch-maven-plugin

MIT 🟠Maven plugin providing Vitest-inspired watch mode for tests with smart selection and parallel execution.

EasyMock

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

JMockit

🔴Integration testing, API mocking and faking, and code coverage.

Mockito

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

MockServer

Apache-2.0 🟢Allows mocking of systems integrated with HTTPS.

Moco

MIT 🟠Concise web services for stubs and mocks.

WireMock

Apache-2.0 🟢Stubs and mocks web services.

Apache JMeter

Apache-2.0 🟢Functional testing and performance measurements.

Gatling

Apache-2.0 🟢Load testing tool designed for ease of use, maintainability and high performance.

JMeter DSL.java

Apache-2.0 🟢Load tests with JMeter as simple as a JUnit test.

bucket4j

Apache-2.0 🟢Rate limiting library based on token-bucket algorithm.

cactoos

MIT 🟢Collection of object-oriented primitives.

fswatch

Apache-2.0 🟢Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.

Guava

Apache-2.0 🟢Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.

ISBN core

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

Java Diff Utils

Apache-2.0 🟢Utilities for text or data comparison and patching.

Java UUID Generator

Apache-2.0 🟢Generates standard UUID versions including time-ordered UUIDv6 and UUIDv7.

java-refined

MIT 🟠Zero-dependency refinement types for Java 8+ with type-safe wrappers covering numerics, strings, and collections.

java-util

Apache-2.0 🟢Zero-dependency, high-performance utilities featuring Converter (universal type conversion), DeepEquals, CaseInsensitiveMap, TTLCache, CompactMap, MultiKeyMap, and object graph traversal.

JEmoji

Apache-2.0 🟢An auto-generated emoji library that provides type-safe direct access to emojis and alias support for Discord, Slack, GitHub and many more features.

Jimfs

Apache-2.0 🟢In-memory file system.

JKScope

Apache-2.0 🔴Java scope functions inspired by Kotlin.

PipelinR

MIT 🟠Small utility library for using handlers and commands with pipelines.

Semver4j

MIT 🟢Lightweight library that helps you handling semantic versioning with different modes.

spring-chain-of-responsibility

Apache-2.0 🟢Autowires Spring Boot beans into a Chain of Responsibility via @Order and @ChainNext, no manual wiring.

Underscore-java

MIT 🟢Port of Underscore.js functions.

Zip4j

Apache-2.0 🟠Reads, writes, encrypts and streams ZIP files.

jabba

Apache-2.0 🟠Java Version Manager inspired by nvm. Supports macOS, Linux and Windows.

jenv

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

SDKMan

Apache-2.0 🟢Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms and Windows.

Apache Nutch

Apache-2.0 🟢Highly extensible, highly scalable web crawler for production environments.

crawlberg

MIT 🟢Crawls and scrapes websites through a Java binding with Markdown conversion and optional browser rendering.

jsoup

MIT 🟢Scrapes, parses, manipulates and cleans HTML.

Norconex Crawler

Apache-2.0 🟢Modular web and file-system crawler with embedded Java APIs, official Docker images and a browser-based configurator.

StormCrawler

Apache-2.0 🟢SDK for building low-latency and scalable web crawlers.

webmagic

Apache-2.0 🟠Scalable crawler with downloading, url management, content extraction and persistent.

ActiveJ

Apache-2.0 🟠Lightweight asynchronous framework built from the ground up for developing high-performance web applications.

Apache Tapestry

Apache-2.0 🟢Component-oriented framework for creating dynamic, robust, highly scalable web applications.

Apache Wicket

Apache-2.0 🟢Component-based web application framework similar to Tapestry, with a stateful GUI.

Blade

Apache-2.0 🟠Lightweight, modular framework that aims to be elegant and simple.

Bootique

Apache-2.0 🟢Minimally opinionated framework for runnable apps.

Erupt

Apache-2.0 🟢Annotation-Driven Low-Code & JPA Visualization.

Javalin

Apache-2.0 🟢Microframework for web applications.

Jooby

Apache-2.0 🟢Scalable, fast and modular micro-framework that offers multiple programming models.

Ninja

Apache-2.0 🟠Full-stack web framework.

Pippo

Apache-2.0 🟠Small, highly modularized, Sinatra-like framework.

Play

Apache-2.0 🟢Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.

PrimeFaces

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

Ratpack

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

Spring Boot

Apache-2.0 🟢Framework for creating stand-alone, production-grade Spring applications.

Takes

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

tinystruct

Apache-2.0 🟢Lightweight, pluggable framework for building Java applications with CLI, HTTP, and modular extension support.

Vaadin

🟢Full-stack Java platform for building browser applications with server-side components.

webforJ

MIT 🟢Full-stack platform that composes the UI in Java on the server using a library of web components.

WebForms Core

A technology for managing HTML tags from the server.

Activiti

Apache-2.0 🟢Embeddable BPMN workflow and business process engine.

Apache DolphinScheduler

Apache-2.0 🟢Distributed workflow orchestration platform with visual and API-driven scheduling.

Cadence Java Client

Apache-2.0 🟢Java client and workflow framework for the Cadence orchestration service.

Conductor

Apache-2.0 🟢Event-driven workflow engine for distributed applications and AI agents.

flowable

Apache-2.0 🟢Compact and efficient workflow and business process management platform.

Maestro

Apache-2.0 🟢Workflow orchestration engine developed by Netflix.

Temporal Java SDK

Apache-2.0 🟢Java SDK for writing durable workflows and activities on Temporal.

Awesome Annotation Processing

Awesome Graal

Awesome Gradle Plugins

Awesome Hybris

Awesome J2ME

Awesome Java libraries and hidden gems

Awesome JVM

JVM 자료모음 (Awesome 계열)

Awesome Microservices

Microservice Architecture related principles and technologies.

Awesome REST

A collaborative list of great resources about RESTful API architecture, development, test, and performance. Feel free to contribute to this ongoing list.

Awesome Selenium

Better than searching Google if you know what you want.

AwesomeJavaFX

ciandcd

Useful Java Links

foojay.io

r/java

Subreddit for the Java community.

Stack Overflow

Question/answer platform.

Design Patterns

Implementation and explanation of the most common design patterns.

FizzBuzz Enterprise Edition

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

Google Java Style

Google's coding standards for source code in the Java™ Programming Language.

Java Algorithms and Clients

Java Concurrency Checklist

Java Developer Roadmap

Java developer roadmap with a current visual learning plan and practice topics.

Java Evolved

Side-by-side comparisons of legacy and modern Java patterns.

Modern Java - A Guide to Java 8

Popular Java 8 guide.

TheCodeForge Java Tutorials

Which JDK

Overview of common JVMs with pros and cons.

Core Java Volume I--Fundamentals

Core Java, Volume II--Advanced Features

Effective Java (3rd Edition)

Head First Java (3rd Edition)

Java Concurrency in Practice

The Well-Grounded Java Developer (2nd Edition)

Thinking in Java

140 Second Ducklings

Short videos on Twitter explaining Java debugging in depth.

A Bootiful Podcast

Foojay Podcast

Inside Java

Official podcast.

Java Off Heap

Adam Bien

Freelance author, JavaOne Rockstar speaker, consultant, Java Champion.

Aleksey Shipilëv

Performance geek, benchmarking czar, concurrency bug hunter.

Antonio Goncalves

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

Arun Gupta

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

Brian Goetz

Java Language Architect at Oracle.

Bruno Borges

Product Manager/Java Jock at Oracle.

Chris Engelbert

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

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

Official Java Twitter 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, Founder and CEO Data Geekery (jOOQ).

Mani Sarkar

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.

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.

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.

Baeldung

In-depth articles and tutorials in the Java ecosystem and web development, with a strong focus on Spring, Spring Security and RESTful APIs.

Dzone

프로그래밍, 웹 개발 및 DevOps 뉴스, 초보자부터 전문가를 위한 튜토리얼 및 도구

InfoQ

개발 팀이 새로운 기술과 관행을 채택할 수 있도록 도움

Java, SQL, and jOOQ

java.libhunt.com

Java.net

Javalobby

JavaWorld

JAXenter

RebelLabs

TheServerSide.com

Vanilla Java