Projects

• Architecture

  • ArchUnit - Test library for specifying and asserting architecture rules.
  • jMolecules - Annotations and interfaces to express design and architecture concepts in code.

• Artificial Intelligence

  • LangChain4j - Simplifies integration of LLMs with unified APIs and a comprehensive toolbox.
  • MCP Java SDK - 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.
  • simple-openai - Library to use the OpenAI API (and compatible ones) in the simplest possible way.
  • JamJet - Agent runtime with a Java SDK for building AI agents, supporting graph-based workflow orchestration, multi-agent coordination, and MCP/A2A protocols.

• Bean Mapping

  • 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.
  • dOOv - Provides fluent API for typesafe domain model validation and mapping. It uses annotations, code generation and a type safe DSL to make bean validation and mapping fast and easy.
  • Selma - Annotation processor-based bean mapper.

• Build

  • Buck2 - Encourages the creation of small, reusable modules consisting of code and resources.
  • Bazel - Tool from Google that builds code quickly and reliably.

• Bytecode Manipulation

  • bytecode-viewer - Java 8 Jar & Android APK reverse engineering suite. (GPL-3.0-only)
  • cglib - Bytecode generation library.
  • Javassist - Tries to simplify bytecode editing.
  • 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.
  • ASM - All-purpose, low-level bytecode manipulation and analysis.
  • Recaf - JVM reverse engineering toolkit, essentially an IDE for Java bytecode.

• Caching

  • Caffeine - High-performance, near-optimal caching library.

• CLI

  • jbock - Reflectionless command line parser.
  • JLine - Includes features from modern shells like completion or history.
  • Jansi - ANSI escape codes to format console output.
  • Text-IO - Aids the creation of full console-based applications.
  • Lanterna - Easy console text-GUI library, similar to curses. (LGPL-3.0-only)
  • Airline - Annotation-based framework for parsing Git-like command-line arguments.
  • Jexer - Advanced console (and Swing) text user interface (TUI) library, with mouse-draggable windows, built-in terminal window manager, and sixel image support. Looks like [Turbo Vision](https://en.wikipedia.org/wiki/Turbo_Vision).
  • AliveJTUI - Declarative, React-style TUI library for building terminal UIs as component trees with diff-based rendering, focus management, and themes.

• Cloud

  • AWS SDK for Java - Provides Java APIs for interacting with Amazon Web Services.
  • Google Cloud Client Libraries - Client libraries for accessing Google Cloud services from Java applications.

• Code Analysis

  • 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.
  • 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.
  • 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)
  • RefactorFirst - Identifies and prioritizes God Classes and Highly Coupled classes.

• Code Coverage

  • Clover - Relies on source-code instrumentation instead of bytecode instrumentation.
  • Cobertura - Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)
  • JaCoCo - Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.
  • Delta Coverage - Computes code coverage of new and modified code based on a provided diff, supporting JaCoCo and IntelliJ coverage engines.

• Code Generators

  • ADT4J - JSR-269 code generator for algebraic data types.
  • Auto - Generates factory, service, and value classes.
  • FreeBuilder - Automatically generates the Builder pattern.
  • Geci - Discovers files that need generated code, updates automatically and writes to the source with a convenient API.
  • JavaPoet - API to generate source files.
  • JHipster - Yeoman source code generator for Spring Boot and AngularJS.
  • Record-Builder - Companion builder class, withers and templates for Java records.
  • EasyEntityToDTO - Annotation processor for automatic DTO and Mapper generation with zero boilerplate.
  • Avaje Http Server - Generates Lightweight JAX-RS style http servers using Javalin or Helidon (Nima) SE.
  • Joda-Beans - Small framework that adds queryable properties to Java, enhancing JavaBeans.
  • Telosys - Simple and light code generator available as an Eclipse Plugin and also as a CLI.
  • JSpecify Package-Info Generator - 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.
  • Bootify ![c - Browser-based Spring Boot app generation with JPA model and REST API.
  • Spring CRUD Generator - Maven plugin for generating Spring Boot CRUD applications from YAML/JSON specifications.

• Compiler-compiler

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

• Computer Vision

  • JavaCV - Java interface to OpenCV, FFmpeg, and much more.

• Configuration

  • 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.
  • dotenv - Twelve-factor configuration library which uses environment-specific files.
  • Externalized Properties - 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 - 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.
  • avaje config - Loads yaml and properties files, supports dynamic configuration, plugins, file-watching and config event listeners.
  • Curator Framework - High-level API for Apache ZooKeeper.
  • KAConf - Annotation-based configuration system for Java and Kotlin.
  • owner - Reduces boilerplate of properties.
  • ini4j - Provides an API for handling Windows' INI files.
  • ClearConfig - Type-safe, composable configuration library with a focus on runtime clarity.

• Constraint Satisfaction Problem Solver

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

• CSV

  • FastCSV - Performance-optimized, dependency-free and RFC 4180 compliant.
  • jackson-dataformat-csv - Jackson extension for reading and writing CSV.
  • uniVocity-parsers - One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.
  • opencsv - Simple CSV parser.

• Database

  • ArangoDB - ArangoDB Java driver.
  • Chronicle Map - Efficient, in-memory (opt. persisted to disk), off-heap key-value 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.
  • HikariCP - High-performance JDBC connection pool.
  • 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).
  • Leaf - Distributed ID generate service.
  • 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.
  • Querydsl - 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.
  • Xodus - Highly concurrent transactional schema-less and ACID-compliant embedded database.
  • CosId - Universal, flexible, high-performance distributed ID generator.
  • Apache ShardingSphere - Distributed SQL transaction & query engine that allows for data sharding, scaling, encryption, and more on any database.
  • Spring Data Dynamic Query - 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.
  • Open J Proxy - Type 3 JDBC driver and Layer 7 proxy server for decoupling applications from relational database connection management.

• Data Structures

  • Big Queue - Fast and persistent queue based on memory-mapped files.
  • HyperMinHash-java - Probabilistic data structure for computing union, intersection, and set cardinality in loglog space.
  • Persistent Collection - Persistent and immutable analogue of the Java Collections Framework.
  • Protobuf - Google's data interchange format.
  • RoaringBitmap - Fast and efficient compressed bitmap.
  • Tape - Lightning-fast, transactional, file-based FIFO.
  • Wire - Clean, lightweight protocol buffers.
  • SBE - Simple Binary Encoding, one of the fastest message formats around.

• Date and Time

  • iCal4j - Parse and build iCalendar 🌎 [RFC 5545](tools.ietf.org/html/rfc5545) 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)
  • Jollyday - Determines the holidays for a given year, country/name and eventually state/region.

• Decentralization

  • java-tron

• Dependency Injection

  • 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.
  • JayWire - Lightweight dependency injection framework. (LGPL-3.0-only)
  • Dimension-DI - JSR-330 runtime dependency injection using the JDK Class-File API.

• Development

  • Faux Pas - Library that simplifies error handling by circumventing the issue that none of the functional interfaces in the Java Runtime is allowed by default to throw checked exceptions.
  • HotswapAgent - Unlimited runtime class and resource redefinition. (GPL-2.0-only)
  • JavaParser - Parse, modify and generate Java code.
  • JavaSymbolSolver - Symbol solver.
  • Manifold - Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.
  • SneakyThrow - Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations.

• Distributed 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.
  • JGroups - Toolkit for reliable messaging and cluster creation.
  • Quasar - 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.

• Distributed Transactions

  • Seata - Delivers high performance and easy to use distributed transaction services under a microservices architecture.

• Distribution

  • Artipie - Binary artifact management toolkit which hosts them on the file system or S3.
  • Boxfuse ![c - 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.
  • Getdown - System for deploying Java applications to end-user computers and keeping them up to date. Developed as an alternative to Java Web Start.
  • 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.
  • jlink.online - Builds optimized runtimes over HTTP.
  • 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.
  • 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.

• Document Processing

  • 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.
  • Sheetz - Library for reading and writing Excel and CSV files with annotation-based mapping, streaming support, and built-in validation.

• Financial

  • 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.

• Formal Verification

  • CATG - Concolic unit testing engine. Automatically generates unit tests using formal methods.
  • Java Path Finder (JPF) - JVM formal verification tool containing a model checker and more. Created by NASA.
  • OpenJML - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)

• Functional Programming

  • 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 Java - 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.
  • Packrat - Gatherers library for Java Stream API. Gatherers can enhance streams with custom intermediate operations.
  • protonpack - Collection of stream utilities.
  • StreamEx - Enhances Java 8 Streams.
  • Parallel Collectors - Stream API Collectors for parallel processing with custom thread pools, designed for I/O-heavy workloads.

• Game Development

  • JBox2D - Port of the renowned C++ 2D physics engine.
  • vulkan4j - Vulkan, OpenGL ES2 and GLFW Memory Allocator bindings.
  • Void2D - High-level 2D game engine with built-in physics based on Swing.

• Geospatial

  • ArcGIS Maps SDK for Java ![c - JavaFX library for adding mapping and GIS functionality to desktop apps.
  • Geo - GeoHash utilities in Java.
  • GraphHopper - Road-routing engine. Used as a Java library or standalone web service.
  • H2GIS - Spatial extension of the H2 database. (LGPL-3.0-only)
  • Mapsforge - Map rendering based on OpenStreetMap data. (LGPL-3.0-only)
  • Spatial4j - General-purpose spatial/geospatial library.

• GUI

  • SnapKit - Modern Java UI library for both desktop and web.
  • Sierra - Lightwieght declarative DSL for rapid development of Swing applications.

• High Performance

  • fastutil - Fast and compact type-specific collections.
  • JCTools - Concurrency tools currently missing from the JDK.
  • Koloboke - Carefully designed extension of the Java Collections Framework with primitive specializations and more.
  • Eclipse Collections - Collections framework inspired by Smalltalk.
  • Agrona - Data structures and utility methods that are common in high-performance applications.
  • fastutil - Fast and compact type-specific collections.

• HTTP Clients

  • Async Http Client - Asynchronous HTTP and WebSocket client library.
  • 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.
  • 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.

• Hypermedia Types

  • hate - Builds hypermedia-friendly objects according to HAL specification.
  • JSON-LD - JSON-LD implementation.
  • Siren4J - Library for the Siren specification.
  • Spring HATEOAS - Standalone and Spring support for building hypermedia-based APIs using HAL, HAL FORMS, Collection+JSON, ALPS and UBER.

• IDE

  • IntelliJ IDEA ![c - Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.