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Awesome

An open API service indexing awesome lists of open source software.

awesome-java

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

Last synced: about 1 hour ago
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  • Resources

  • Projects

    • Bytecode Manipulation

      • ASM - All-purpose, low-level bytecode manipulation and analysis.
      • Byte Buddy - Further simplifies bytecode generation with a fluent API.
      • Perses - Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.
      • 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.
      • Recaf - JVM reverse engineering toolkit, essentially an IDE for Java bytecode.
      • ASM - All-purpose, low-level bytecode manipulation and analysis.
      • Byte Buddy - Further simplifies bytecode generation with a fluent API.
      • Byteman - Manipulate bytecode at runtime via DSL (rules); mainly for testing/troubleshooting. (LGPL-2.1-or-later)
      • bytecode-viewer - Java 8 Jar & Android APK reverse engineering suite. (GPL-3.0-only)

    • Caching

      • cache2k - In-memory high performance caching library.
      • Ehcache - Distributed general-purpose cache.
      • Infinispan - Highly concurrent key/value datastore used for caching.
      • Caffeine - High-performance, near-optimal caching library.
      • cache2k - In-memory high performance caching library.
      • Infinispan - Highly concurrent key/value datastore used for caching.

    • CLI

      • JCommander - Command-line argument-parsing framework with custom types and validation via implementing interfaces.
      • picocli - ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.
      • 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).
      • Lanterna - Easy console text-GUI library, similar to curses. (LGPL-3.0-only)
      • Airline - Annotation-based framework for parsing Git-like command-line arguments.
      • 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.
      • jbock - Reflectionless command line parser.

    • Cluster Management

      • Apache Aurora - Mesos framework for long-running services and cron jobs.
      • Singularity - Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.

    • Code Analysis

      • jQAssistant - Static code analysis with Neo4J-based query language. (GPL-3.0-only)
      • PMD - Source code analysis for finding bad coding practices.
      • 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.
      • 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.
      • RefactorFirst - Identifies and prioritizes God Classes and Highly Coupled classes.
      • jQAssistant - Static code analysis with Neo4J-based query language. (GPL-3.0-only)
      • NullAway - Eliminates NullPointerExceptions with low build-time overhead.
      • Spotbugs - Static analysis of bytecode to find potential bugs. (LGPL-2.1-only)

    • Code Generators

      • Bootify ![c - Browser-based Spring Boot app generation with JPA model and REST API.
      • Immutables - Annotation processors to generate simple, safe and consistent value objects.
      • JPA Buddy ![c - 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.
      • JavaPoet - API to generate source files.
      • ADT4J - JSR-269 code generator for algebraic data types.
      • FreeBuilder - Automatically generates the Builder pattern.
      • Geci - Discovers files that need generated code, updates automatically and writes to the source with a convenient API.
      • Record-Builder - Companion builder class, withers and templates for Java records.
      • 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.
      • Immutables - Annotation processors to generate simple, safe and consistent value objects.
      • Lombok - Code generator that aims to reduce verbosity.
      • Auto - Generates factory, service, and value classes.
      • Avaje Http Server - Generates Lightweight JAX-RS style http servers using Javalin or Helidon (Nima) SE.
      • EasyEntityToDTO - Annotation processor for automatic DTO and Mapper generation with zero boilerplate.
      • JHipster - Yeoman source code generator for Spring Boot and AngularJS.
      • Joda-Beans - Small framework that adds queryable properties to Java, enhancing JavaBeans.

    • Compiler-compiler

      • JFlex - Lexical analyzer generator.
      • JavaCC - Parser generator that generates top-down parsers. Allows lexical state switching and permits extended BNF specifications.
      • ANTLR - Complex full-featured framework for top-down parsing.
      • JFlex - Lexical analyzer generator.

    • Computer Vision

      • 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.

    • Configuration

      • ini4j - Provides an API for handling Windows' INI files.
      • microconfig - 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.
      • dotenv - Twelve-factor configuration library which uses environment-specific files.
      • 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.
      • Configurate - Configuration library with support for various configuration formats and transformations.
      • owner - Reduces boilerplate of properties.
      • microconfig - 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.
      • avaje config - Loads yaml and properties files, supports dynamic configuration, plugins, file-watching and config event listeners.
      • centraldogma - Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.
      • config - Configuration library supporting Java properties, JSON or its human optimized superset HOCON.
      • Curator Framework - High-level API for Apache ZooKeeper.
      • Externalized Properties - Lightweight yet powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism.
      • KAConf - Annotation-based configuration system for Java and Kotlin.

    • Constraint Satisfaction Problem Solver

      • Choco - Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques.
      • OptaPlanner - Business planning and resource scheduling optimization solver.
      • Timefold - Flexible solver with Spring/Quarkus support and quickstarts for the Vehicle Routing Problem, Maintenance Scheduling, Employee Shift Scheduling and much more.
      • JaCoP - Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models. (AGPL-3.0)
      • Choco - Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques.
      • OptaPlanner - Business planning and resource scheduling optimization solver.

    • CSV

      • opencsv - Simple CSV parser.
      • FastCSV - Performance-optimized, dependency-free and RFC 4180 compliant.
      • jackson-dataformat-csv - Jackson extension for reading and writing CSV.
      • Super CSV - Powerful CSV parser with support for Dozer, Joda-Time and Java 8.
      • uniVocity-parsers - One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.

    • Data Structures

      • Apache Avro - Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.
      • Apache Orc - Fast and efficient columnar storage format for Hadoop-based workloads.
      • 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.
      • Big Queue - Fast and persistent queue based on memory-mapped files.
      • Protobuf - Google's data interchange format.
      • Tape - Lightning-fast, transactional, file-based FIFO.
      • Wire - Clean, lightweight protocol buffers.
      • SBE - Simple Binary Encoding, one of the fastest message formats around.
      • Apache Orc - Fast and efficient columnar storage format for Hadoop-based workloads.
      • RoaringBitmap - Fast and efficient compressed bitmap.

    • Database

      • Apache Calcite - Dynamic data management framework. It contains many of the pieces that comprise a typical database management system.
      • Apache Drill - Distributed, schema on-the-fly, ANSI SQL query engine for Big Data exploration.
      • Apache Phoenix - High-performance relational database layer over HBase for low-latency applications.
      • druid - High-performance, column-oriented, distributed data store.
      • H2 - Small SQL database notable for its in-memory functionality.
      • JDBI - Convenient abstraction of JDBC.
      • Lettuce - Lettuce is a scalable Redis client for building non-blocking Reactive applications.
      • MapDB - Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.
      • Querydsl - Typesafe unified queries.
      • Trino - Distributed SQL query engine for big data.
      • Vibur DBCP - JDBC connection pool library with advanced performance monitoring capabilities.
      • CosId - Universal, flexible, high-performance distributed ID generator.
      • jetcd - Client library for etcd.
      • Apache ShardingSphere - Distributed SQL transaction & query engine that allows for data sharding, scaling, encryption, and more on any database.
      • ArangoDB - ArangoDB Java driver.
      • Chronicle Map - Efficient, in-memory (opt. persisted to disk), off-heap key-value store.
      • Debezium - Low latency data streaming platform for change data capture.
      • 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.
      • HSQLDB - HyperSQL 100% Java database.
      • Jest - Client for the Elasticsearch REST API.
      • MariaDB4j - Launcher for MariaDB that requires no installation or external dependencies.
      • 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.
      • Jedis - Small client for interaction with Redis, with methods for commands.
      • Apache Calcite - Dynamic data management framework. It contains many of the pieces that comprise a typical database management system.
      • Apache Drill - Distributed, schema on-the-fly, ANSI SQL query engine for Big Data exploration.
      • druid - High-performance, column-oriented, distributed data store.
      • Liquibase - Database-independent library for tracking, managing and applying database schema changes.
      • Vibur DBCP - JDBC connection pool library with advanced performance monitoring capabilities.
      • Jinq - Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ).
      • Leaf - Distributed ID generate service.
      • 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.
      • Trino - Distributed SQL query engine for big data.
      • Xodus - Highly concurrent transactional schema-less and ACID-compliant embedded database.

    • Dependency Injection

      • Apache DeltaSpike - CDI extension framework.
      • HK2 - Lightweight and dynamic dependency injection framework.
      • Inversion of Control
      • Apache DeltaSpike - CDI extension framework.
      • Avaje Inject - Microservice-focused compile-time injection framework without reflection.
      • Dagger - Compile-time injection framework without reflection.
      • Feather - Ultra-lightweight, JSR-330-compliant dependency injection library.
      • Governator - Extensions and utilities that enhance Google Guice.
      • Guice - Lightweight and opinionated framework that completes Dagger.
      • HK2 - Lightweight and dynamic dependency injection framework.
      • JayWire - Lightweight dependency injection framework. (LGPL-3.0-only)

    • Development

      • AspectJ - Seamless aspect-oriented programming extension.
      • DCEVM - JVM modification that allows unlimited redefinition of loaded classes at runtime. (GPL-2.0-only)
      • NoException - Allows checked exceptions in functional interfaces and converts exceptions to Optional return.
      • HotswapAgent - Unlimited runtime class and resource redefinition. (GPL-2.0-only)
      • JavaSymbolSolver - Symbol solver.
      • AspectJ - Seamless aspect-oriented programming extension.
      • DCEVM - JVM modification that allows unlimited redefinition of loaded classes at runtime. (GPL-2.0-only)
      • Faux Pas - Library that simplifies error handling by circumventing the issue that none of the functional interfaces in the Java Runtime is allowed by default to throw checked exceptions.
      • JavaParser - Parse, modify and generate Java code.
      • Manifold - Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.
      • NoException - Allows checked exceptions in functional interfaces and converts exceptions to Optional return.
      • SneakyThrow - Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations.
      • Tail - Enable infinite recursion using tail call optimization.

    • Distributed Applications

      • Apache Geode - In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.
      • Apache Storm - Realtime computation system.
      • Atomix - Fault-tolerant distributed coordination framework.
      • Axon - Framework for creating CQRS applications.
      • JGroups - Toolkit for reliable messaging and cluster creation.
      • Dropwizard Circuit Breaker - Circuit breaker design pattern for Dropwizard. (GPL-2.0-only)
      • Hazelcast - Highly scalable in-memory datagrid with a free open-source version.
      • Atomix - Fault-tolerant distributed coordination framework.
      • Failsafe - Simple failure handling with retries and circuit breakers.
      • Quasar - Lightweight threads and actors for the JVM.
      • JGroups - Toolkit for reliable messaging and cluster creation.
      • 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.
      • Apache Geode - In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.
      • Axon - Framework for creating CQRS applications.
      • Zuul - Gateway service that provides dynamic routing, monitoring, resiliency, security, and more.

    • Distributed Transactions

      • Atomikos - Provides transactions for REST, SOA and microservices with support for JTA and XA.
      • Narayana - Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards. (LGPL-2.1-only)
      • Atomikos - Provides transactions for REST, SOA and microservices with support for JTA and XA.
      • Narayana - Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards. (LGPL-2.1-only)
      • Seata - Delivers high performance and easy to use distributed transaction services under a microservices architecture.

    • Distribution

      • Boxfuse ![c - Deployment of JVM applications to AWS using the principles of immutable infrastructure.
      • Central Repository - Largest binary component repository available as a free service to the open-source community. Default used by Apache Maven, and available in all other build tools.
      • Cloudsmith ![c - Fully managed package management SaaS with support for Maven/Gradle/SBT with a free tier.
      • jDeploy - Deploy desktop apps as native Mac, Windows or Linux bundles.
      • Nexus ![c - Binary management with proxy and caching capabilities.
      • 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.
      • IzPack - Setup authoring tool for cross-platform deployments.
      • Boxfuse ![c - Deployment of JVM applications to AWS using the principles of immutable infrastructure.
      • Central Repository - Largest binary component repository available as a free service to the open-source community. Default used by Apache Maven, and available in all other build tools.
      • Nexus ![c - Binary management with proxy and caching capabilities.
      • Artipie - Binary artifact management toolkit which hosts them on the file system or S3.
      • 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.

    • Document Processing

      • Apache POI - Supports OOXML (XLSX, DOCX, PPTX) as well as OLE2 (XLS, DOC or PPT).
      • documents4j - API for document format conversion using third-party converters such as MS Word.
      • docx4j - Create and manipulate Microsoft Open XML files.
      • fastexcel - High performance library to read and write large Excel (XLSX) worksheets.
      • zerocell - Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead.
      • Apache POI - Supports OOXML (XLSX, DOCX, PPTX) as well as OLE2 (XLS, DOC or PPT).

    • Formal Verification

      • 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)
      • JMLOK 2.0 - Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected. (GPL-3.0-only)
      • Checker Framework - Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)
      • 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)
      • CATG - Concolic unit testing engine. Automatically generates unit tests using formal methods.
      • 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.

    • Game Development

      • JBox2D - Port of the renowned C++ 2D physics engine.
      • jMonkeyEngine - Game engine for modern 3D development.
      • LWJGL - Robust framework that abstracts libraries like OpenGL/CL/AL.
      • Mini2Dx - Beginner-friendly, master-ready framework for rapidly prototyping and building 2D games.
      • Void2D - High-level 2D game engine with built-in physics based on Swing.
      • Litiengine - AWT-based, lightweight 2D game engine.
      • FXGL - JavaFX Game Development Framework.
      • JBox2D - Port of the renowned C++ 2D physics engine.
      • libGDX - All-round cross-platform, high-level framework.
      • LWJGL - Robust framework that abstracts libraries like OpenGL/CL/AL.
      • vulkan4j - Vulkan, OpenGL ES2 and GLFW Memory Allocator bindings.

    • Geospatial

      • Apache SIS - Library for developing geospatial applications.
      • GeoTools - Library that provides tools for geospatial data. (LGPL-2.1-only)
      • H2GIS - Spatial extension of the H2 database. (LGPL-3.0-only)
      • ArcGIS Maps SDK for Java ![c - JavaFX library for adding mapping and GIS functionality to desktop apps.
      • Apache SIS - Library for developing geospatial applications.
      • GeoTools - Library that provides tools for geospatial data. (LGPL-2.1-only)
      • Geo - GeoHash utilities in Java.
      • GraphHopper - Road-routing engine. Used as a Java library or standalone web service.
      • Jgeohash - Library for using the GeoHash algorithm.
      • Mapsforge - Map rendering based on OpenStreetMap data. (LGPL-3.0-only)
      • Spatial4j - General-purpose spatial/geospatial library.

    • GUI

      • JavaFX - Successor of Swing.
      • SWT - Graphical widget toolkit.
      • JavaFX - Successor of Swing.
      • Scene Builder - Visual layout tool for JavaFX applications.
      • SnapKit - Modern Java UI library for both desktop and web.

    • HTTP Clients

      • Avaje Http Client - Wrapper on JDK 11's HttpClient that adds Feign-like interface among other enhancements.
      • unirest-java - Simplified, lightweight HTTP client library.
      • methanol - HTTP client extensions library.
      • Retrofit - Typesafe REST client.
      • Apache HttpComponents - Toolset of low-level Java components focused on HTTP and associated protocols.
      • 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.
      • Ribbon - Client-side IPC library that is battle-tested in the cloud.
      • Riptide - Client-side response routing for Spring's RestTemplate.

    • IDE

      • jGRASP - Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer.
      • Eclipse - Established open-source project with support for lots of plugins and languages.
      • jGRASP - Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer.
      • IntelliJ IDEA ![c - Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.
      • SnapCode - Modern IDE for Java running in the browser, focused on education.
      • Visual Studio Code - Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace.

    • Introspection

      • Mirror - Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.
      • Objenesis - Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions.
      • jOOR - jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package.
      • Mirror - Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.
      • ReflectASM - ReflectASM is a very small Java library that provides high performance reflection by using code generation.
      • Reflections - Reflections scans your classpath, indexes the metadata, allows you to query it on runtime and may save and collect that information for many modules within your project.
      • ClassGraph - ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.

    • JSON

      • Genson - Powerful and easy-to-use Java-to-JSON conversion library.
      • JsonSurfer - Streaming JsonPath processor dedicated to processing big and complicated JSON data.
      • Jackson - Similar to GSON, but offers performance gains if you need to instantiate the library more often.
      • Avaje Jsonb - Reflection-free Json binding via source code generation with Jackson-like annotations.
      • jackson-modules-java8 - Set of Jackson modules for Java 8 datatypes and features.
      • DSL-JSON - JSON library with advanced compile time databinding.
      • Gson - Serializes objects to JSON and vice versa. Good performance with on-the-fly usage.
      • HikariJSON - High-performance JSON parser, 2x faster than Jackson.
      • Genson - Powerful and easy-to-use Java-to-JSON conversion library.
      • Jackson-datatype-money - Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types.
      • JSON-io - Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer.
      • LoganSquare - JSON parsing and serializing library based on Jackson's streaming API. Outperforms GSON & Jackson's library.
      • Moshi - Modern JSON library, less opinionated and uses built-in types like List and Map.
      • Yasson - Binding layer between classes and JSON documents similar to JAXB.
      • fastjson - Very fast processor with no additional dependencies and full data binding.
      • Jolt - JSON to JSON transformation tool.
      • JsonPath - Extract data from JSON using XPATH-like syntax.

    • JVM and JDK

      • Adopt Open JDK - Community-driven OpenJDK builds, including both HotSpot and OpenJ9.
      • Liberica JDK - Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)
      • Open JDK - Open JDK community home. (GPL-2.0-only WITH Classpath-exception-2.0)
      • Zulu - OpenJDK builds for Windows, Linux, and macOS. (GPL-2.0-only WITH Classpath-exception-2.0)
      • OpenJ9 - High performance, enterprise-calibre, flexibly licensed, openly-governed cross-platform JVM extending and augmenting the runtime technology components from the Eclipse OMR and OpenJDK project.
      • Dragonwell8 - Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.
      • SAP Machine - SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)
      • Microsoft JDK - Microsoft Build of OpenJDK, Free, Open Source, Freshly Brewed!
      • Adopt Open JDK - Community-driven OpenJDK builds, including both HotSpot and OpenJ9.
      • Which JDK - Overview of common JVMs with pros and cons.
      • Corretto - No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)
      • Graal - Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)
      • Open JDK - Open JDK community home. (GPL-2.0-only WITH Classpath-exception-2.0)
      • ParparVM - VM with non-blocking, concurrent GC for iOS. (GPL-2.0-only WITH Classpath-exception-2.0)
      • RedHat Open JDK - RedHat's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)

    • Logging

      • Apache Log4j 2 - Complete rewrite with a powerful plugin and configuration architecture.
      • Graylog - Open-source aggregator suited for extended role and permission management. (GPL-3.0-only)
      • Logback - Robust logging library with interesting configuration options via Groovy.
      • SLF4J - Abstraction layer/simple logging facade.
      • Logstash - Tool for managing log files.
      • Kibana - Analyzes and visualizes log files. Some features require payment.
      • Apache Log4j 2 - 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.
      • Logbook - Extensible, open-source library for HTTP request and response logging.
      • p6spy - Enables logging for all JDBC transactions without changes to the code.
      • OpenTracing Toolbox - Collection of libraries that build on top of OpenTracing and provide extensions and plugins to existing instrumentations.
      • Flogger - 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)
      • Logback - Robust logging library with interesting configuration options via Groovy.

    • Machine Learning

      • Apache Mahout - Scalable algorithms focused on collaborative filtering, clustering and classification.
      • DatumBox - Provides several algorithms and pre-trained models for natural language processing.
      • DJL - High-level and engine-agnostic framework for deep learning.
      • oj! Algorithms - High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing.
      • Intelligent java - Seamlessly integrate with remote deep learning and language models programmatically.
      • Siddhi - Cloud native streaming and complex event processing engine.
      • Tribuo - Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.
      • JSAT - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)
      • m2cgen - CLI tool to transpile models into native code.
      • Neureka - A lightweight, platform independent, OpenCL accelerated nd-array/tensor library.
      • Oryx 2 - Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
      • Apache Flink - Fast, reliable, large-scale data processing engine.
      • Apache Mahout - Scalable algorithms focused on collaborative filtering, clustering and classification.
      • Deeplearning4j - Distributed and multi-threaded deep learning library.
      • Smile - Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.

    • Messaging

      • Apache ActiveMQ - Message broker that implements JMS and converts synchronous to asynchronous communication.
      • Apache Camel - Glues together different transport APIs via Enterprise Integration Patterns.
      • Apache Pulsar - Distributed pub/sub-messaging system.
      • Apache RocketMQ - Fast, reliable, and scalable distributed messaging platform.
      • Apache Qpid - Apache Qpid makes messaging tools that speak AMQP and support many languages and platforms.
      • Hermes - Fast and reliable message broker built on top of Kafka.
      • Deezpatch - Simple, lightweight, and performant dispatch library for decoupling messages (requests and events) and message handlers.
      • EventBus - Simple publish/subscribe event bus.
      • Nakadi - Provides a RESTful API on top of Kafka.
      • RabbitMQ Java client - RabbitMQ client.
      • JeroMQ - Implementation of ZeroMQ.
      • Apache ActiveMQ - Message broker that implements JMS and converts synchronous to asynchronous communication.
      • Apache Camel - Glues together different transport APIs via Enterprise Integration Patterns.
      • Apache Kafka - High-throughput distributed messaging system.
      • Apache Pulsar - Distributed pub/sub-messaging system.
      • Apache RocketMQ - Fast, reliable, and scalable distributed messaging platform.
      • Apache Qpid - Apache Qpid makes messaging tools that speak AMQP and support many languages and platforms.
      • Aeron - Efficient, reliable, unicast and multicast message transport.
      • AutoMQ - AutoMQ is a cloud-native, serverless reinvented Kafka that is easily scalable, manage-less and cost-effective.
      • Smack - Cross-platform XMPP client library.
      • NATS client - NATS client.

    • Microservice

      • ActiveRPC - Lightweight and fast library for complex high-load distributed applications and Memcached-like solutions.
      • Nacos - Dynamic service discovery, configuration and service management platform for building cloud native applications.
      • Quarkus - Kubernetes stack tailored for the HotSpot and Graal VM.
      • KeenType - Modernized version of a Java-based implementation of the New Typesetting System, which was heavily based on Donald E. Knuth's original TeX.
      • Eureka - REST-based service registry for resilient load balancing and failover.
      • JDA - Wrapping of the Discord REST API and its WebSocket events.
      • ActiveRPC - Lightweight and fast library for complex high-load distributed applications and Memcached-like solutions.
      • Helidon - Two-style approach for writing microservices: Functional-reactive and as an implementation of MicroProfile.
      • Nacos - Dynamic service discovery, configuration and service management platform for building cloud native applications.
      • Quarkus - Kubernetes stack tailored for the HotSpot and Graal VM.
      • Armeria - Asynchronous RPC/REST client/server library built on top of Java 8, Netty, HTTP/2, Thrift and gRPC.
      • consul-api - Client for the Consul API: a distributed, highly available and datacenter-aware registry/discovery service.
      • kubernetes-client - Client provides access to the full Kubernetes & OpenShift REST APIs via a fluent DSL.
      • OpenAI-Java - Java libraries for using OpenAI's GPT-3 API.
      • Sentinel - Flow control component enabling reliability, resilience and monitoring for microservices.

    • Miscellaneous

      • JBake - Static website generator.
      • JCuda - JCuda offers Java bindings for CUDA and CUDA-related libraries.
      • JPad - Snippet runner.
      • OpenRefine - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
      • Togglz - Implementation of the Feature Toggles pattern.
      • Membrane Service Proxy - Open-source, reverse-proxy framework.
      • PipelinR - Small utility library for using handlers and commands with pipelines.
      • Polyglot for Maven - Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.
      • RR4J - RR4J is a tool that records java bytecode execution and later allows developers to replay locally.
      • Simple Java Mail - Mailing with a clean and fluent API.
      • Smooks - Framework for fragment-based message processing. (Apache-2.0 OR LGPL-3.0-or-later)
      • JPad - Snippet runner.
      • JObfuscator![c - Source code obfuscator.
      • FF4J - Feature Flags for Java.
      • FizzBuzz Enterprise Edition - No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)
      • IP2Location.io Java SDK - Wrapper for the IP2Location.io Geolocation API and the IP2WHOIS domain WHOIS API.
      • J2ObjC - Java-to-Objective-C translator for porting Android libraries to iOS.
      • JBang - JBang makes it easy to use Java for scripting. It lets you use a single file for
      • OpenRefine - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
      • CQEngine - Ultra-fast, SQL-like queries on Java collections.
      • Design Patterns - Implementation and explanation of the most common design patterns.
      • ISBN core - A small library that contains a representation object of ISBN-10 and ISBN-13 and tools to parse, validate and format one.
      • JBot - Framework for building chatbots. (GPL-3.0-only)
      • JCuda - JCuda offers Java bindings for CUDA and CUDA-related libraries.
      • JEmoji - 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 - In-memory file system.
      • Joda-Money - Basic currency and money classes and algorithms not provided by the JDK.
      • jOOX - Simple wrapper for the org.w3c.dom package, to allow for fluent XML document creation and manipulation with an API inspired by jQuery.
      • jsweet - Source transpiler to TypeScript/JavaScript.
      • Maven Wrapper - Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.
      • MinimalFTP - Lightweight, small and customizable FTP server.
      • LittleProxy - High performance HTTP proxy atop Netty's event-based networking library.
      • Modern Java - A Guide to Java 8 - Popular Java 8 guide.
      • Modernizer - Detect uses of legacy Java APIs.
      • OctoLinker - Browser extension which allows to navigate through code on GitHub more efficiently.
      • Svix - Library for the Svix API to send webhooks and verify signatures.
      • TypeTools - Tools for resolving generic types.
      • webcam-capture - Library for using built-in and external webcams directly in Java.
      • XMLBeam - Processes XML by using annotations or XPath within code.
      • yGuard - Obfuscation via renaming and shrinking.

    • Mobile Development

      • Codename One - Cross-platform solution for writing native mobile apps. (GPL-2.0-only WITH Classpath-exception-2.0)
      • MobileUI - Cross-platform framework for developing mobile apps with native UI in Java and Kotlin.
      • Multi-OS Engine - Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.
      • MobileUI - Cross-platform framework for developing mobile apps with native UI in Java and Kotlin.
      • Multi-OS Engine - Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.

    • Monitoring

      • Glowroot - Open-source Java APM.
      • inspectIT - Captures detailed run-time information via hooks that can be changed on the fly. It supports tracing over multiple systems via the OpenTracing API and can correlate the data with end user monitoring.
      • Jolokia - JMX over REST.
      • zipkin - Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures.
      • Failsafe Actuator - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
      • HertzBeat - Real-time monitoring system with custom-monitor and agentless.
      • hippo4j - Dynamic and observable thread pool framework.
      • Sysmon - Lightweight platform monitoring tool for Java VMs.
      • Pinpoint - Open-source APM tool.
      • Jaeger client - Jaeger client.
      • JavaMelody - Performance monitoring and profiling.
      • jmxtrans - Connect to multiple JVMs and query them for their attributes via JMX. Its query language is based on JSON, which allows non-Java programmers to access the JVM attributes. Supports different output writes, including Graphite, Ganglia, and StatsD.
      • Micrometer - Vendor-neutral metrics/observability facade for the most popular metrics/observability libraries.
      • Micrometer Tracing - Vendor-neutral distributed tracing facade for the most popular tracer libraries.
      • Glowroot - Open-source Java APM.
      • Apitally - Simple, privacy-focused API monitoring, analytics and request logging for Spring Boot apps.
      • Automon - Combines the power of AOP with monitoring and/or logging tools.
      • Datadog ![c - Modern monitoring & analytics.
      • Dropwizard Metrics - Expose metrics via JMX or HTTP and send them to a database.
      • nudge4j - Remote developer console from the browser for Java 8 via bytecode injection.
      • OpenTelemetry - Instrument, generate, collect, and export telemetry data to help you analyze your software’s performance and behavior.
      • Prometheus - Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.
      • Sentry ![c - Integration with [Sentry](https://github.com/getsentry/sentry), an application error tracking and performance analysis platform.
      • SPM ![c - Performance monitor with distributing transaction tracing for JVM apps.
      • Stagemonitor - Open-source performance monitoring and transaction tracing for JVM apps.

    • Natural Language Processing

      • DKPro - Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.
      • LingPipe - Toolkit for tasks ranging from POS tagging to sentiment analysis.
      • CogCompNLP - Provides common annotators for plain text input. (Research and Academic Use License)
      • CoreNLP - Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis. (GPL-3.0-or-later)
      • Hypherator - 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.

    • Networking

      • MINA - Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.
      • Undertow - Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly. (LGPL-2.1-only)
      • Comsat - Integrates standard Java web-related APIs with Quasar fibers and actors.
      • Dubbo - High-performance RPC framework.
      • KryoNet - Provides a clean and simple API for efficient TCP and UDP client/server network communication using NIO and Kryo.
      • Fluency - High throughput data ingestion logger to Fluentd and Fluent Bit.
      • Grizzly - NIO framework. Used as a network layer in Glassfish.
      • gRPC-java - RPC framework based on protobuf and HTTP/2.
      • urnlib - Represent, parse and encode URNs, as in RFC 2141. (GPL-3.0-only)
      • sshj - Programmatically use SSH, SCP or SFTP.
      • MINA - Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.
      • Netty - Framework for building high-performance network applications.
      • Commons-networking - Client for server-sent events (SSE).
      • Drift - Easy-to-use, annotation-based library for creating Thrift clients and serializable types.
      • ServiceTalk - Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.
      • TLS Channel - Implements a ByteChannel interface over SSLEngine, enabling easy-to-use (socket-like) TLS.

    • ORM

      • 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.
      • Ebean - Provides simple and fast data access.
      • EclipseLink - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
      • Hibernate - Robust and widely used, with an active community. (LGPL-2.1-only)
      • Doma - Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.
      • MyBatis - Couples objects with stored procedures or SQL statements.
      • MyBatis-Plus - A powerful enhanced toolkit of MyBatis for simplifying development.
      • ObjectiveSql - ActiveRecord ORM for rapid development and convention over configuration.
      • Permazen - Language-natural persistence layer.
      • SimpleFlatMapper - Simple database and CSV mapper.
      • Ebean - Provides simple and fast data access.
      • EclipseLink - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
      • Hibernate - Robust and widely used, with an active community. (LGPL-2.1-only)

    • PaaS

    • PDF

      • Apache PDFBox - Toolbox for creating and manipulating PDFs.
      • Dynamic Jasper - Abstraction layer to JasperReports. (LGPL-3.0-only)
      • Apache FOP - Creates PDFs from XSL-FO.
      • Dynamic Jasper - Abstraction layer to JasperReports. (LGPL-3.0-only)
      • iText ![c - Creates PDF files programmatically.
      • Dynamic Jasper - Abstraction layer to JasperReports. (LGPL-3.0-only)
      • DynamicReports - Simplifies JasperReports. (LGPL-3.0-only)
      • Tabula - Extracts tables from PDF files.
      • Eclipse BIRT - 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)
      • JasperReports - Complex reporting engine. (LGPL-3.0-only)
      • Open HTML to PDF - Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.
      • OpenPDF - Open-source iText fork. (LGPL-3.0-only & MPL-2.0)

    • Performance analysis

      • fastThread ![c - Analyze and visualize thread dumps with a free cloud-based upload interface.
      • JMH - Harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM. (GPL-2.0 only WITH Classpath-exception-2.0)
      • fastThread ![c - Analyze and visualize thread dumps with a free cloud-based upload interface.
      • GCeasy ![c - Tool to analyze and visualize GC logs. It provides a free cloud-based upload interface.
      • honest-profiler - Low-overhead, bias-free sampling profiler.
      • jHiccup - Logs and records platform JVM stalls.
      • JITWatch - Analyze the JIT compiler optimisations made by the HotSpot JVM.
      • JMH - Harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM. (GPL-2.0 only WITH Classpath-exception-2.0)
      • LatencyUtils - Utilities for latency measurement and reporting.

    • Platform

      • BCEL - Byte Code Engineering Library - analyze, create, and manipulate Java class files.
      • BeanUtils - Easy-to-use wrappers around the Java reflection and introspection APIs.
      • BeanUtils2 - Redesign of Commons BeanUtils.
      • BSF - Bean Scripting Framework - interface to scripting languages, including JSR-223.
      • ClassScan - Find Class interfaces, methods, fields, and annotations without loading.
      • CLI - Command-line arguments parser.
      • CLI2 - Redesign of Commons CLI.
      • Codec - General encoding/decoding algorithms, e.g. phonetic, base64 or URL.
      • Collections - Extends or augments the Java Collections Framework.
      • Compress - Defines an API for working with tar, zip and bzip2 files.
      • Configuration - Reading of configuration/preferences files in various formats.
      • Convert - Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another.
      • CSV - Component for reading and writing comma separated value files.
      • Daemon - Alternative invocation mechanism for unix-daemon-like java code.
      • DBCP - Database connection pooling services.
      • DbUtils - JDBC helper library.
      • Digester - XML-to-Java-object mapping utility.
      • Email - Library for sending e-mail from Java.
      • Exec - API for dealing with external process execution and environment management in Java.
      • FileUpload - File upload capability for your servlets and web applications.
      • Finder - Java library inspired by the UNIX find command.
      • Flatfile - Java library for working with flat data structures.
      • Graph - 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 - Image library.
      • IO - Collection of I/O utilities.
      • Javaflow - Continuation implementation to capture the state of the application.
      • JCI - Java Compiler Interface.
      • JCS - Java Caching System.
      • Jelly - XML based scripting and processing engine.
      • Jexl - 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 - Utilities for manipulating Java Beans using the XPath syntax.
      • Lang - Provides extra functionality for classes in java.lang.
      • 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 - 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 - Generic object pooling component.
      • SCXML - Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.
      • Validator - Framework to define validators and validation rules in an xml file.
      • VFS - Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.
      • Weaver - Provides an easy way to enhance (weave) compiled bytecode.
      • CUBA Platform - High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.
      • Light-4J - Fast, lightweight and productive microservices framework with built-in [security](https://github.com/networknt/light-oauth2/).
      • Logging - Wrapper around a variety of logging API implementations.
      • RDF - Common implementation of RDF 1.1 that could be implemented by systems on the JVM.
      • RNG - Commons Rng provides implementations of pseudo-random numbers generators.
      • Spring - Provides many packages for dependency injection, aspect-oriented programming, security, etc.
      • CSV - Component for reading and writing comma separated value files.
      • Email - Library for sending e-mail from Java.
      • IO - Collection of I/O utilities.
      • Lang - Provides extra functionality for classes in java.lang.
      • Net - Collection of network utilities and protocol implementations.
      • OGNL - Object-graph navigation language.
      • 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 - Generic object pooling component.
      • Proxy - Library for creating dynamic proxies.
      • SCXML - Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.
      • Validator - Framework to define validators and validation rules in an xml file.
      • VFS - Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.
      • Weaver - Provides an easy way to enhance (weave) compiled bytecode.
      • CUBA Platform - High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.
      • Orienteer - Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.

    • REST Frameworks

      • Jersey - JAX-RS reference implementation.
      • Elide - Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.
      • Rapidoid - Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.
      • RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
      • Spark - Sinatra inspired framework.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Swagger - Standard, language-agnostic interface to REST APIs.
      • RestExpress - Thin wrapper on the JBoss Netty HTTP stack that provides scaling and performance.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • Elide - Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.
      • Jersey - JAX-RS reference implementation.
      • Rapidoid - Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.
      • RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
      • Spark - Sinatra inspired framework.
      • Swagger - Standard, language-agnostic interface to REST APIs.
      • Dropwizard - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
      • Microserver - Convenient, extensible microservices plugin system for Spring & Spring Boot. With more than 30 plugins and growing, it supports both micro-monolith and pure microservices styles.
      • rest.li - Framework for building robust, scalable RESTful architectures using typesafe bindings and asynchronous, non-blocking IO with an end-to-end developer workflow that promotes clean practices, uniform interface design and consistent data modeling.
      • Restlet Framework - Pioneering framework with powerful routing and filtering capabilities, and a unified client and server API.
      • Crnk - Implementation of the JSON API specification to build resource-oriented REST endpoints with sorting, filtering, paging, linking, object graphs, type-safety, bulk updates, integrations and more.
      • springdoc-openapi - Automates the generation of API documentation using Spring Boot projects.
      • openapi-generator - Allows generation of API client libraries, SDKs, server stubs, documentation and configuration automatically given an OpenAPI Spec.

    • Reactive libraries

      • Akka - Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.
      • RxJava - Allows for composing asynchronous and event-based programs using observable sequences.
      • vert.x - Polyglot event-driven application framework.
      • Akka - Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.
      • Reactive Streams - Provides a standard for asynchronous stream processing with non-blocking backpressure.
      • Reactor - A framework for building non-blocking applications on the JVM, providing support for reactive programming.

    • Science

      • GraphStream - Library for modeling and analyzing dynamic graphs.
      • JFreeChart - 2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)
      • JGraphT - Graph library that provides mathematical graph-theory objects and algorithms.
      • JGraphX - Library for visualizing (mainly Swing) and interacting with node-edge graphs.
      • BioJava - Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.
      • LogicNG - Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas.
      • Mines Java Toolkit - Library for geophysical scientific computation, visualization and digital signal analysis.
      • Tablesaw - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.
      • XChart - Light-weight library for plotting data. Many customizable chart types are available.
      • Morpheus - Provides a versatile two-dimensional memory efficient tabular data structure called a DataFrame to enable efficient in-memory analytics for scientific computing on the JVM.
      • Orekit - A low level space flight dynamics library providing basic elements (orbits, dates, attitude, frames...) and various algorithms (conversions, propagations, pointing...) to handle them.
      • GraphStream - Library for modeling and analyzing dynamic graphs.
      • JFreeChart - 2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)
      • Chart-FX - 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 - Modular, light and easy graph framework for theoretic algorithms.
      • Orson-Charts - Generates a wide variety of 3D charts that can be displayed with Swing and JavaFX or exported to PDF, SVG, PNG and JPEG. (GPL-3.0-only)
      • Apache Lucene - High-performance, full-featured, cross-platform, text search engine library.
      • Apache Solr - Enterprise search engine optimized for high-volume traffic.
      • Elasticsearch - Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.
      • Elasticsearch - Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.
      • Apache Lucene - High-performance, full-featured, cross-platform, text search engine library.
      • Apache Solr - Enterprise search engine optimized for high-volume traffic.
      • Indexer4j - Simple and light full text indexing and searching library.

    • Security

      • Apache Shiro - Performs authentication, authorization, cryptography and session management.
      • Bouncy Castle - All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.
      • Keycloak - Integrated SSO and IDM for browser apps and RESTful web services.
      • OACC - Provides permission-based authorization services.
      • Passay - Enforce password policy by validating candidate passwords against a configurable rule set.
      • Topaz - Fine-grained authorization for applications with support for RBAC, ABAC, and ReBAC.
      • Jwks RSA - JSON Web Key Set parser.
      • Kalium - Binding for the Networking and Cryptography (NaCl) library.
      • Keywhiz - System for distributing and managing secrets.
      • Nbvcxz - Advanced password strength estimation.
      • Hdiv - Runtime application that repels application security risks included in the OWASP Top 10, including SQL injection, cross-site scripting, cross-site request forgery, data tampering, and brute force attacks.
      • jjwt - JSON web token for Java and Android.
      • Password4j - User-friendly cryptographic library that supports Argon2, Bcrypt, Scrypt, PBKDF2 and various other cryptographic hash functions.
      • SecurityBuilder - Fluent Builder API for JCA and JSSE classes and especially X.509 certificates.
      • Tink - Provides a simple and misuse-proof API for common cryptographic tasks.
      • OACC - Provides permission-based authorization services.
      • Themis - Multi-platform high-level cryptographic library provides easy-to-use encryption for protecting sensitive data: secure messaging with forward secrecy, secure data storage (AES256GCM); suits for building end-to-end encrypted applications.
      • Keycloak - Integrated SSO and IDM for browser apps and RESTful web services.
      • Apache Shiro - Performs authentication, authorization, cryptography and session management.
      • Cryptomator - Multiplatform, transparent, client-side encryption of files in the cloud. (GPL-3.0-only)
      • Passay - Enforce password policy by validating candidate passwords against a configurable rule set.
      • Topaz - Fine-grained authorization for applications with support for RBAC, ABAC, and ReBAC.
      • Ayza - High-level SSL configuration builder for configuring HTTP clients and servers with SSL/TLS.
      • Bouncy Castle - All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.
      • DependencyCheck - Detects publicly disclosed vulnerabilities contained within a project's dependencies.
      • jwt-java - Easily create and parse JSON Web Tokens and create customized JWT validators using a fluent API.
      • OpenAM - Access management solution that includes authentication, SSO, authorization, federation, entitlements and web services security.
      • OTP-Java - One-time password generator library according to RFC 4226 (HOTP) and RFC 6238 (TOTP).
      • pac4j - Security engine.

    • Server

      • Apache Tomcat - Robust, all-round server for Servlet and JSP.
      • Apache TomEE - Tomcat plus Java EE.
      • WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)
      • nanohttpd - Tiny, easily embeddable HTTP server.
      • Apache Tomcat - Robust, all-round server for Servlet and JSP.
      • Apache TomEE - Tomcat plus Java EE.
      • Jetty - Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations.
      • WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)

    • Template Engine

      • Freemarker - Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.
      • Pebble - Inspired by Twig and separates itself with its inheritance feature and its easy-to-read syntax. It ships with built-in autoescaping for security and it includes integrated support for internationalization.
      • Thymeleaf - Aims to be a substitute for JSP and works for XML files.
      • Jade4J - Implementation of Pug (formerly known as Jade).
      • jstachio - Typesafe Mustache templating engine.
      • Handlebars.java - Logicless and semantic Mustache templates.
      • jte - Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.
      • Jtwig - Modular, configurable and fully tested template engine.
      • Rocker - Optimized, memory efficient and speedy template engine producing statically typed, plain objects.
      • Freemarker - Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.
      • Pebble - Inspired by Twig and separates itself with its inheritance feature and its easy-to-read syntax. It ships with built-in autoescaping for security and it includes integrated support for internationalization.
      • Thymeleaf - Aims to be a substitute for JSP and works for XML files.
      • Jamal - Extendable template engine embedded into Maven/JavaDoc, supporting multiple extensions (Groovy, Ruby, JavaScript, JShell, PlantUml) with support for snippet handling.
      • StringTemplate - Template engine for generating source code, web pages, emails, or any other formatted text output.

    • Testing

      • JGiven - Provides a fluent API which allows for simpler composition.
      • Apache JMeter - Functional testing and performance measurements.
      • Arquillian - Integration and functional testing platform for Java EE containers.
      • Citrus - Integration testing framework that focuses on both client- and server-side messaging.
      • JUnit - Common testing framework.
      • jqwik - Engine for property-based testing built on JUnit 5.
      • PIT - Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.
      • Hamcrest - Matchers that can be combined to create flexible expressions of intent.
      • Truth - Google's fluent assertion and proposition framework.
      • pojo-tester - Automatically performs tests on basic POJO methods. (LGPL-3.0-only)
      • JMockit - Integration testing, API mocking and faking, and code coverage.
      • MockServer - Allows mocking of systems integrated with HTTPS.
      • WireMock - Stubs and mocks web services.
      • REST Assured - DSL for easy testing of REST/HTTP services.
      • EasyMock - EasyMock is a Java library that provides an easy way to use Mock Objects in unit testing.
      • Pact JVM - Consumer-driven contract testing.
      • Karate - DSL that combines API test-automation, mocks and performance-testing making testing REST/HTTP services easy.
      • jFairy - Fake data generator.
      • Instancio - Automates data setup in unit tests by generating fully-populated, reproducible objects. Includes JUnit 5 extension.
      • Randomized Testing - JUnit test runner and plugins for running JUnit tests with pseudo-randomness.
      • Java Faker - Port of Ruby's fake data generator.
      • Mockneat - Another fake data generator.
      • cdi-test - JUnit extension for easy and efficient testing of CDI components.
      • selenium - Browser automation framework and ecosystem.
      • AssertJ - Fluent assertions that improve readability.
      • LogCaptor - Captures log entries for unit testing purposes.
      • log-capture - Captures log entries and provides assertions for unit and integration testing.
      • Mutability Detector - Reports whether instances of a given class are immutable.
      • raml-tester - Tests if a request/response matches a given RAML definition.
      • Selfie - Snapshot testing (inline and on disk).
      • JMeter DSL.java - Load tests with JMeter as simple as a JUnit test.
      • JMockit - Integration testing, API mocking and faking, and code coverage.
      • Mockito - Mocking framework that lets you write tests with a clean and simple API.
      • Moco - Concise web services for stubs and mocks.
      • PowerMock - Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.
      • JSONAssert - Simplifies testing JSON strings.
      • JUnit - Common testing framework.
      • weld-testing - Set of test framework extensions (JUnit 4, JUnit 5, Spock) to enhance the testing of CDI components via Weld. Supports Weld 5.
      • Awaitility - DSL for synchronizing asynchronous operations.
      • 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 - Supports generating test data or combining scenarios for parameterized tests.
      • Beanmother - Sets up beans from YAML fixtures.
      • JBehave - Extensively configurable framework that describes stories.
      • JGiven - Provides a fluent API which allows for simpler composition.
      • Apache JMeter - Functional testing and performance measurements.
      • Arquillian - Integration and functional testing platform for Java EE containers.
      • Citrus - Integration testing framework that focuses on both client- and server-side messaging.
      • Gatling - Load testing tool designed for ease of use, maintainability and high performance.
      • jqwik - Engine for property-based testing built on JUnit 5.
      • PIT - Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.
      • Hamcrest - Matchers that can be combined to create flexible expressions of intent.
      • JSONAssert - Simplifies testing JSON strings.
      • Truth - Google's fluent assertion and proposition framework.
      • pojo-tester - Automatically performs tests on basic POJO methods. (LGPL-3.0-only)
      • MockServer - Allows mocking of systems integrated with HTTPS.
      • WireMock - Stubs and mocks web services.
      • ConcurrentUnit - Toolkit for testing multi-threaded and asynchronous applications.
      • GreenMail - In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL. (GPL-2.0-only)
      • Hoverfly Java - Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services.
      • WebTau - Test across REST-API, Graph QL, Browser, Database, CLI and Business Logic with consistent set of matchers and concepts.
      • Cucumber - Provides a way to describe features in a plain language which customers can understand.
      • Cukes-REST - Collection of Gherkin steps for REST-service testing using Cucumber.
      • J8Spec - Follows a Jasmine-like syntax.
      • Lamdba Behave - Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.
      • Datafaker - Modern fake data generator forked from Java Faker.
      • Fixture Factory - Generates fake objects from a template.
      • JMock - JMock is a high-performance data generation and simulation component library implemented in Java.
      • JsonUnit - Library that simplifies JSON comparison in tests.
      • XMLUnit - Simplifies testing for XML output.
      • ConsoleCaptor - Captures console output for unit testing purposes.
      • junit-dataprovider - TestNG-like data provider/runner for JUnit.
      • junit-pioneer - JUnit 5 extension pack, pushing the frontiers on Jupiter.
      • Stebz - Multi-approach framework for test steps managing.
      • Testcontainers - Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

    • Utility

      • Protégé - Provides an ontology editor and a framework to build knowledge-based systems.
      • bucket4j - Rate limiting library based on token-bucket algorithm.
      • dregex - Regular expression engine that uses deterministic finite automata. It supports some Perl-style features and yet retains linear matching time, and also offers set operations.
      • fswatch - Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.
      • Gephi - Cross-platform for visualizing and manipulating large graph networks. (GPL-3.0-only)
      • Guava - Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.
      • JADE - Framework and environment for building and debugging multi-agent systems. (LGPL-2.0-only)
      • Javadoc Publisher - Generate Javadoc from your maven/gradle project and deploy it automatically on GitHub Page.
      • Java Diff Utils - Utilities for text or data comparison and patching.
      • JavaVerbalExpressions - Library that helps with constructing difficult regular expressions.
      • JGit - Lightweight, pure Java library implementing the Git version control system.
      • JKScope - Java scope functions inspired by Kotlin.
      • minio-java - Provides simple APIs to access any Amazon S3-compatible object storage server.
      • Protégé - Provides an ontology editor and a framework to build knowledge-based systems.
      • Semver4j - Lightweight library that helps you handling semantic versioning with different modes.
      • Underscore-java - Port of Underscore.js functions.
      • Arthas - Allows to troubleshoot production issues for applications without modifying code or restarting servers.
      • cactoos - Collection of object-oriented primitives.
      • Chocotea - Generates postman collection, environment and integration tests from java code.
      • CRaSH - Provides a shell into a JVM that's running CRaSH. Used by Spring Boot and others. (LGPL-2.1-or-later)
      • Dex - Java/JavaFX tool capable of powerful ETL and data visualization.
      • Embulk - Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.

    • Web Crawling

      • Apache Nutch - Highly extensible, highly scalable web crawler for production environments.
      • jsoup - Scrapes, parses, manipulates and cleans HTML.
      • webmagic - Scalable crawler with downloading, url management, content extraction and persistent.
      • Apache Nutch - Highly extensible, highly scalable web crawler for production environments.
      • StormCrawler - SDK for building low-latency and scalable web crawlers.
      • Crawler4j - Simple and lightweight web crawler.
      • jsoup - Scrapes, parses, manipulates and cleans HTML.

    • Web Frameworks

      • ActiveJ - Lightweight asynchronous framework built from the ground up for developing high-performance web applications.
      • Apache Tapestry - Component-oriented framework for creating dynamic, robust, highly scalable web applications.
      • Apache Wicket - Component-based web application framework similar to Tapestry, with a stateful GUI.
      • Bootique - Minimally opinionated framework for runnable apps.
      • Firefly - Asynchronous framework for rapid development of high-performance web application.
      • Jooby - Scalable, fast and modular micro-framework that offers multiple programming models.
      • Ninja - Full-stack web framework.
      • Pippo - Small, highly modularized, Sinatra-like framework.
      • Play - Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.
      • PrimeFaces - 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.
      • Vaadin - Event-driven framework that uses standard web components. Server-side architecture with Ajax on the client side.
      • PrimeFaces - JSF framework with both free and commercial/support versions and frontend components.
      • Vaadin - Full-stack open-source Java framework that simplifies web app development. Build complex, interactive applications with Java alone, and enhance with TypeScript and React components, without needing deep JavaScript, CSS, or HTML expertise.
      • ActiveJ - Lightweight asynchronous framework built from the ground up for developing high-performance web applications.
      • Apache Tapestry - Component-oriented framework for creating dynamic, robust, highly scalable web applications.
      • Apache Wicket - Component-based web application framework similar to Tapestry, with a stateful GUI.
      • Bootique - Minimally opinionated framework for runnable apps.
      • Firefly - Asynchronous framework for rapid development of high-performance web application.
      • Javalin - Microframework for web applications.
      • Pippo - Small, highly modularized, Sinatra-like framework.
      • Jooby - Scalable, fast and modular micro-framework that offers multiple programming models.
      • Ninja - Full-stack web framework.
      • Play - Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.
      • Ratpack - Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications.
      • Blade - Lightweight, modular framework that aims to be elegant and simple.
      • Takes - Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.
      • WebForms Core - A technology for managing HTML tags from the server.

    • Workflow Orchestration Engines

      • Cadence - Stateful code platform from Uber.
      • Temporal - Microservice orchestration platform, forked from Cadence but gRPC based.
      • Cadence - Stateful code platform from Uber.
      • flowable - Compact and efficient workflow and business process management platform.
      • Temporal - Microservice orchestration platform, forked from Cadence but gRPC based.

    • Artificial Intelligence

      • LangChain4j - Simplifies integration of LLMs with unified APIs and a comprehensive toolbox.
      • simple-openai - Library to use the OpenAI API (and compatible ones) in the simplest possible way.
      • 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.

    • 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.
      • 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.
      • Orika - JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.
      • 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.
      • reMap - Lambda and method handle-based mapping which requires code and not annotations if objects have different names.
      • Selma - Annotation processor-based bean mapper.

    • Build

      • Buck - Encourages the creation of small, reusable modules consisting of code and resources.
      • Bazel - Tool from Google that builds code quickly and reliably.
      • Gradle - Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven's dependency management.
      • Buck2 - Encourages the creation of small, reusable modules consisting of code and resources.
      • Apache Maven - 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.

    • High Performance

      • Eclipse Collections - Collections framework inspired by Smalltalk.
      • HPPC - Primitive collections.
      • Disruptor - Inter-thread messaging library.
      • JCTools - Concurrency tools currently missing from the JDK.
      • Koloboke - Carefully designed extension of the Java Collections Framework with primitive specializations and more.

    • Serialization

      • Fury - Blazing fast object graph serialization framework powered by JIT and zero-copy.
      • FlatBuffers - Memory-efficient serialization library that can access serialized data without unpacking and parsing it.
      • Kryo - Fast and efficient object graph serialization framework.
      • MessagePack - Efficient binary serialization format.
      • Fury - Blazing fast object graph serialization framework powered by JIT and zero-copy.
      • PHP Serializer - Serializing objects in the PHP serialization format.
      • FST - JDK-compatible, high-performance object graph serialization.

    • Architecture

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

    • Cloud

    • Native

      • Aparapi - Converts bytecode to OpenCL which allows execution on GPUs.
      • JavaCPP - Provides efficient and easy access to native C++.
      • native-lib-loader - Native library loader for extracting and loading native libraries from Java.
      • JNA - Work with native libraries without writing JNI. Also provides interfaces to common system libraries.
      • JNR - Work with native libraries without writing JNI. Also provides interfaces to common system libraries. Same goals as JNA, but faster, and serves as the basis for the upcoming [Project Panama](http://openjdk.java.net/projects/panama).

    • Date and Time

      • iCal4j - Parse and build iCalendar [RFC 5545](https://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)

    • Functional Programming

      • Cyclops - Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.
      • Functional Java - Implements numerous basic and advanced programming abstractions that assist composition-oriented development.
      • derive4j - Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms. (GPL-3.0-only)
      • Fugue - Functional extensions to Guava.
      • jOOλ - Extension to Java 8 that aims to fix gaps in lambda by providing numerous missing types and a rich set of sequential Stream API additions.
      • 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.

    • Imagery

      • image-comparison - Library that compares 2 images with the same sizes and shows the differences visually by drawing rectangles. Some parts of the image can be excluded from the comparison.
      • vips-ffm - Comprehensive bindings for libvips, using Java's "Foreign Function & Memory" API.
      • scrimage - Immutable, functional, and performant JVM library for manipulation of images.
      • Barcode-Lib4J - 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.
      • Imgscalr - Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.
      • Tess4J - JNA wrapper for Tesseract OCR API.
      • Thumbnailator - High-quality thumbnail generation library.
      • TwelveMonkeys - Collection of plugins that extend the number of supported image file formats.
      • ZXing - Multi-format 1D/2D barcode image processing library.

    • Job Scheduling

      • Sundial - Lightweight framework to simply define jobs, define triggers and start the scheduler.
      • db-scheduler - Persistent and cluster-friendly scheduler.
      • easy-batch - Set up batch jobs with simple processing pipelines. Records are read in sequence from a data source, processed in pipeline and written in batches to a data sink.
      • Wisp - Simple library with minimal footprint and straightforward API.
      • JobRunr - Job scheduling library which utilizes lambdas for fire-and-forget, delayed and recurring jobs. Guarantees execution by single scheduler instance using optimistic locking. Has features for persistence, minimal dependencies and is embeddable.
      • Quartz - Feature-rich, open source job scheduling library that can be integrated within virtually any Java application.
      • shedlock - Makes sure that your scheduled tasks are executed at most once at the same time. If a task is being executed on one node, it acquires a lock which prevents execution of the same task from another node or thread.

    • Hypermedia Types

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

    • Version Managers

      • jabba - Java Version Manager inspired by nvm. Supports macOS, Linux and Windows.
      • jenv - Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and macOS.
      • SDKMan - Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms and Windows.

    • Pathfinding

      • Pathetic - A highly configurable 3D A* pathfinding library that uses specific optimizations for high performance.

    • Processes

      • ch.vorburger.exec - Convenient API around Apache Commons Exec.
      • zt-exec - Provides a unified API to Apache Commons Exec and ProcessBuilder.
      • zt-process-killer - Stops processes started from Java or the system processes via PID.

    • Decentralization

    • 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.

    • 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.
Programming Languages
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Keywords
java 205 kotlin 15 android 14 spring-boot 14 spring 13 testing 13 monitoring 12 microservices 12 static-analysis 11 jvm 11 database 9 http 9 java-library 9 json 9 javascript 8 awesome 8 rest 7 rest-api 7 xml 7 rpc 7 annotation-processor 7 awesome-list 6 high-performance 6 metrics 6 jdbc 6 java-8 6 static-code-analysis 6 serialization 6 sql 6 javafx 6 library 6 machine-learning 6 python 6 test-automation 5 orm 5 java8 5 gradle 5 scheduler 5 grpc 5 groovy 5 c 5 framework 5 junit 5 configuration 5 cpp 5 cloud-native 5 performance 4 mocking 4 web 4 security 4