# Awesome Java

A curated list of awesome Java frameworks, libraries and software.

## Contents

- Projects
  - Bean Mapping
  - Build
  - Bytecode Manipulation
  - Caching
  - CLI
  - Cluster Management
  - Code Analysis
  - Code Coverage
  - Code Generators
  - Compiler-compiler
  - Computer Vision
  - Configuration
  - Constraint Satisfaction Problem Solver
  - CSV
  - Data Structures
  - Database
  - Date and Time
  - Dependency Injection
  - Development
  - Distributed Applications
  - Distributed Transactions
  - Distribution
  - Document Processing
  - Financial
  - Formal Verification
  - Functional Programming
  - Game Development
  - Geospatial
  - GUI
  - High Performance
  - HTTP Clients
  - Hypermedia Types
  - IDE
  - Imagery
  - Introspection
  - Job Scheduling
  - JSON
  - JVM and JDK
  - Logging
  - Machine Learning
  - Messaging
  - Microservice
  - Miscellaneous
  - Mobile Development
  - Monitoring
  - Native
  - Natural Language Processing
  - Networking
  - ORM
  - PaaS
  - PDF
  - Performance analysis
  - Platform
  - Processes
  - Reactive libraries
  - REST Frameworks
  - Science
  - Search
  - Security
  - Serialization
  - Server
  - Template Engine
  - Testing
  - Utility
  - Version Managers
  - Web Crawling
  - Web Frameworks
  - Workflow Orchestration Engines
- Resources
  - Related Awesome Lists
  - Communities
  - Frontends
  - Influential Books
  - Podcasts and Screencasts
  - People
  - Websites
- Contributing

## Projects

### Bean Mapping

Frameworks that ease bean mapping.

- dOOv - Provides fluent API for typesafe domain model validation and mapping. It uses annotations, code generation and a type safe DSL to make bean validation and mapping fast and easy.
- JMapper - Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.
- MapStruct - Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.
- ModelMapper - Intelligent object mapping library that automatically maps objects to each other.
- Orika - JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.
- reMap - Lambda and method handle-based mapping which requires code and not annotations if objects have different names.
- Selma - Annotation processor-based bean mapper.

### Build

Tools that handle the build cycle and dependencies of an application.

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

### Bytecode Manipulation

Libraries to manipulate bytecode programmatically.

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

### Caching

Libraries that provide caching facilities.

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

### CLI

Libraries for everything related to the CLI.

#### Argument Parsing

Libraries to assist with parsing command line arguments.

- Airline - Annotation-based framework for parsing Git-like command-line arguments.
- JCommander - Command-line argument-parsing framework with custom types and validation via implementing interfaces.
- jbock - Reflectionless command line parser.
- JLine - Includes features from modern shells like completion or history.
- picocli - ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.

#### Text-Based User Interfaces

Libraries that provide TUI frameworks, or building blocks related functions.

- Jansi - ANSI escape codes to format console output.
- Jexer - Advanced console (and Swing) text user interface (TUI) library, with mouse-draggable windows, built-in terminal window manager, and sixel image support. Looks like Turbo Vision.
- Text-IO - Aids the creation of full console-based applications.
- Lanterna - Easy console text-GUI library, similar to curses. (LGPL-3.0-only)

### Cluster Management

Frameworks that can dynamically manage applications inside of a cluster.

- 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

Tools that provide metrics and quality measurements.

- 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.
- jQAssistant - Static code analysis with Neo4J-based query language. (GPL-3.0-only)
- NullAway - Eliminates NullPointerExceptions with low build-time overhead.
- PMD - Source code analysis for finding bad coding practices.
- p3c - Provides Alibaba’s coding guidelines for PMD, IDEA and Eclipse.
- RefactorFirst - Identifies and prioritizes God Classes and Highly Coupled classes.
- SonarJava - Static analyzer for SonarQube & SonarLint. (LGPL-3.0-only)
- Spoon - Library for analyzing and transforming Java source code.
- Spotbugs - Static analysis of bytecode to find potential bugs. (LGPL-2.1-only)

### Code Coverage

Frameworks and tools that enable code coverage metrics collection for test suites.

- 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.

### Code Generators

Tools that generate patterns for repetitive code in order to reduce verbosity and error-proneness.

- ADT4J - JSR-269 code generator for algebraic data types.
- Auto - Generates factory, service, and value classes.
- Avaje Http Server - Generates Lightweight JAX-RS style http servers using Javalin or Helidon (Nima) SE.
- Bootify - Browser-based Spring Boot app generation with JPA model and REST API.
- FreeBuilder - Automatically generates the Builder pattern.
- Geci - Discovers files that need generated code, updates automatically and writes to the source with a convenient API.
- Immutables - Annotation processors to generate simple, safe and consistent value objects.
- JavaPoet - API to generate source files.
- JHipster - Yeoman source code generator for Spring Boot and AngularJS.
- Joda-Beans - Small framework that adds queryable properties to Java, enhancing JavaBeans.
- JPA Buddy - Plugin for IntelliJ IDEA. Provides visual tools for generating JPA entities, Spring Data JPA repositories, Liquibase changelogs and SQL scripts. Offers automatic Liquibase/Flyway script generation by comparing model to DB, and reverse engineering JPA entities from DB tables.
- Lombok - Code generator that aims to reduce verbosity.
- 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.

### Compiler-compiler

Frameworks that help to create parsers, interpreters or compilers.

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

### Computer Vision

Libraries which seek to gain high level information from images and videos.

- 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

Libraries that provide external configuration.

- 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.
- Configurate - Configuration library with support for various configuration formats and transformations.
- Curator Framework - High-level API for Apache ZooKeeper.
- dotenv - Twelve-factor configuration library which uses environment-specific files.
- Externalized Properties - Lightweight yet powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism.
- Gestalt - Gestalt offers a comprehensive solution to the challenges of configuration management. It allows you to source configuration data from multiple inputs, merge them intelligently, and present them in a structured, type-safe manner.
- ini4j - Provides an API for handling Windows’ INI files.
- KAConf - Annotation-based configuration system for Java and Kotlin.
- 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.
- owner - Reduces boilerplate of properties.

### Constraint Satisfaction Problem Solver

Libraries that help with implementing optimization and satisfiability problems.

- Choco - Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques.
- JaCoP - Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models. (AGPL-3.0)
- 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.

### CSV

Frameworks and libraries that simplify reading/writing CSV data.

- FastCSV - Performance-optimized, dependency-free and RFC 4180 compliant.
- jackson-dataformat-csv - Jackson extension for reading and writing CSV.
- opencsv - Simple CSV parser.
- 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

Efficient and specific 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.
- Apache Parquet - Columnar storage format based on assembly algorithms from Google’s paper on Dremel.
- Apache Thrift - Data interchange format that originated at Facebook.
- Big Queue - Fast and persistent queue based on memory-mapped files.
- HyperMinHash-java - Probabilistic data structure for computing union, intersection, and set cardinality in loglog space.
- Persistent Collection - Persistent and immutable analogue of the Java Collections Framework.
- Protobuf - Google’s data interchange format.
- RoaringBitmap - Fast and efficient compressed bitmap.
- SBE - Simple Binary Encoding, one of the fastest message formats around.
- Tape - Lightning-fast, transactional, file-based FIFO.
- Wire - Clean, lightweight protocol buffers.

### Database

Everything that simplifies interactions with the 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.
- 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.
- druid - High-performance, column-oriented, distributed data store.
- eXist - NoSQL document database and application platform. (LGPL-2.1-only)
- FlexyPool - Brings metrics and failover strategies to the most common connection pooling solutions.
- Flyway - Simple database migration tool.
- H2 - Small SQL database notable for its in-memory functionality.
- HikariCP - High-performance JDBC connection pool.
- HSQLDB - HyperSQL 100% Java database.
- JDBI - Convenient abstraction of JDBC.
- Jedis - Small client for interaction with Redis, with methods for commands.
- Jest - Client for the Elasticsearch REST API.
- jetcd - Client library for etcd.
- Jinq - Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ).
- jOOQ - Generates typesafe code based on SQL schema.
- Leaf - Distributed ID generate service.
- Lettuce - Lettuce is a scalable Redis client for building non-blocking Reactive applications.
- Liquibase - Database-independent library for tracking, managing and applying database schema changes.
- MapDB - Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.
- MariaDB4j - Launcher for MariaDB that requires no installation or external dependencies.
- Modality - Lightweight ORM with database reverse engineering features.
- OpenDJ - LDAPv3 compliant directory service, developed for the Java platform, providing a high performance, highly available, and secure store for the identities.
- 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.
- Trino - Distributed SQL query engine for big data.
- Vibur DBCP - JDBC connection pool library with advanced performance monitoring capabilities.
- Xodus - Highly concurrent transactional schema-less and ACID-compliant embedded database.
- CosId - Universal, flexible, high-performance distributed ID generator.

### Date and Time

Libraries related to handling date and time.

- iCal4j - Parse and build iCalendar RFC 5545 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)

### Dependency Injection

Libraries that help to realize the Inversion of Control paradigm.

- 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

Augmentation of the development process at a fundamental level.

- 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.
- 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.
- 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

Libraries and frameworks for writing distributed and fault-tolerant applications.

- Apache Geode - In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.
- Apache Storm - Realtime computation system.
- Apache ZooKeeper - Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.
- Atomix - Fault-tolerant distributed coordination framework.
- Axon - Framework for creating CQRS applications.
- Dropwizard Circuit Breaker - Circuit breaker design pattern for Dropwizard. (GPL-2.0-only)
- Failsafe - Simple failure handling with retries and circuit breakers.
- Hazelcast - Highly scalable in-memory datagrid with a free open-source version.
- 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

Distributed transactions provide a mechanism for ensuring consistency of data updates in the presence of concurrent access and partial failures.

- Atomikos - Provides transactions for REST, SOA and microservices with support for JTA and XA.
- Bitronix - Simple but complete implementation of the JTA 1.1 API.
- 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

Tools that handle the distribution of applications in native formats.

- Artipie - Binary artifact management toolkit which hosts them on the file system or S3.
- Boxfuse - Deployment of JVM applications to AWS using the principles of immutable infrastructure.
- Capsule - Simple and powerful packaging and deployment. A fat JAR on steroids, or a “Docker for Java” that supports JVM-optimized containers.
- Central Repository - Largest binary component repository available as a free service to the open-source community. Default used by Apache Maven, and available in all other build tools.
- Cloudsmith - Fully managed package management SaaS with support for Maven/Gradle/SBT with a free tier.
- Getdown - System for deploying Java applications to end-user computers and keeping them up to date. Developed as an alternative to Java Web Start.
- IzPack - Setup authoring tool for cross-platform deployments.
- JavaPackager - Maven and Gradle plugin which provides an easy way to package Java applications in native Windows, macOS or GNU/Linux executables, and generate installers for them.
- jDeploy - Deploy desktop apps as native Mac, Windows or Linux bundles.
- jlink.online - Builds optimized runtimes over HTTP.
- Nexus - Binary management with proxy and caching capabilities.
- packr - Packs JARs, assets and the JVM for native distribution on Windows, Linux and macOS.
- really-executable-jars-maven-plugin - Maven plugin for making self-executing JARs.

### Document Processing

Libraries that assist with processing office document formats.

- 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.

### Financial

Libraries related to the financial domain.

- 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

Formal-methods tools: proof assistants, model checking, symbolic execution, etc.

- CATG - Concolic unit testing engine. Automatically generates unit tests using formal methods.
- Checker Framework - Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)
- Daikon - Detects likely program invariants and generates JML specs based on those invariants.
- Java Path Finder (JPF) - JVM formal verification tool containing a model checker and more. Created by NASA.
- JMLOK 2.0 - Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected. (GPL-3.0-only)
- KeY - Formal software development tool that aims to integrate design, implementation, formal specification, and formal verification of object-oriented software as seamlessly as possible. Uses JML for specification and symbolic execution for verification. (GPL-2.0-or-later)
- OpenJML - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)

### Functional Programming

Libraries that facilitate 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)
- Fugue - Functional extensions to Guava.
- 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.
- protonpack - Collection of stream utilities.
- StreamEx - Enhances Java 8 Streams.
- Vavr - Functional component library that provides persistent data types and functional control structures.

### Game Development

Frameworks that support the development of games.

- FXGL - JavaFX Game Development Framework.
- JBox2D - Port of the renowned C++ 2D physics engine.
- jMonkeyEngine - Game engine for modern 3D development.
- libGDX - All-round cross-platform, high-level framework.
- Litiengine - AWT-based, lightweight 2D game engine.
- 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.

### Geospatial

Libraries for working with geospatial data and algorithms.

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

### GUI

Libraries to create modern graphical user interfaces.

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

### High Performance

Everything about high-performance computation, from collections to specific libraries.

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

### HTTP Clients

Libraries that assist with creating HTTP requests and/or binding responses.

- Apache HttpComponents - Toolset of low-level Java components focused on HTTP and associated protocols.
- Async Http Client - Asynchronous HTTP and WebSocket client library.
- Avaje Http Client - Wrapper on JDK 11’s HttpClient that adds Feign-like interface among other enhancements.
- Feign - HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.
- Google HTTP Client - Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf.
- methanol - HTTP client extensions library.
- Retrofit - Typesafe REST client.
- Ribbon - Client-side IPC library that is battle-tested in the cloud.
- Riptide - Client-side response routing for Spring’s RestTemplate.
- unirest-java - Simplified, lightweight HTTP client library.

### Hypermedia Types

Libraries that handle serialization to hypermedia types.

- hate - Builds hypermedia-friendly objects according to HAL specification.
- JSON-LD - JSON-LD implementation.
- Siren4J - Library for the Siren specification.

### IDE

Integrated development environments that try to simplify several aspects of development.

- Eclipse - Established open-source project with support for lots of plugins and languages.
- IntelliJ IDEA - Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.
- jGRASP - Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer.
- NetBeans - Provides integration for several Java SE and EE features, from database access to HTML5.
- SnapCode - Modern IDE for Java running in the browser, focused on education.
- Visual Studio Code - Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace.

### Imagery

Libraries that assist with the creation, evaluation or manipulation of graphical images.

- Imgscalr - Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.
- Tess4J - JNA wrapper for Tesseract OCR API.
- Thumbnailator - High-quality thumbnail generation library.
- TwelveMonkeys - Collection of plugins that extend the number of supported image file formats.
- ZXing - Multi-format 1D/2D barcode image processing library.
- image-comparison - Library that compares 2 images with the same sizes and shows the differences visually by drawing rectangles. Some parts of the image can be excluded from the comparison.

### Introspection

Libraries that help make the Java introspection and reflection API easier and faster to use.

- ClassGraph - ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.
- jOOR - jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package.
- Mirror - 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.
- 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.

### Job Scheduling

Libraries for scheduling background jobs.

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

### JSON

Libraries for serializing and deserializing JSON to and from Java objects.

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

### JVM and JDK

Current implementations of the JVM/JDK.

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

### Logging

Libraries that log the behavior of an application.

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

### Machine Learning

Tools that provide specific statistical algorithms for learning from data.

- Apache Flink - Fast, reliable, large-scale data processing engine.
- Apache Mahout - Scalable algorithms focused on collaborative filtering, clustering and classification.
- DatumBox - Provides several algorithms and pre-trained models for natural language processing.
- Deeplearning4j - Distributed and multi-threaded deep learning library.
- DJL - High-level and engine-agnostic framework for deep learning.
- H2O - Analytics engine for statistics over big data.
- Intelligent java - Seamlessly integrate with remote deep learning and language models programmatically.
- JSAT - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)
- m2cgen - CLI tool to transpile models into native code.
- Neureka - A lightweight, platform independent, OpenCL accelerated nd-array/tensor library.
- oj! Algorithms - High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing.
- Oryx 2 - Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
- Siddhi - Cloud native streaming and complex event processing engine.
- Smile - Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.
- Tribuo - Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.
- Weka - Collection of algorithms for data mining tasks ranging from pre-processing to visualization. (GPL-3.0-only)

### Messaging

Tools that help send messages between clients to ensure protocol independency.

- Aeron - Efficient, reliable, unicast and multicast message transport.
- 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.
- AutoMQ - AutoMQ is a cloud-native, serverless reinvented Kafka that is easily scalable, manage-less and cost-effective.
- Deezpatch - Simple, lightweight, and performant dispatch library for decoupling messages (requests and events) and message handlers.
- EventBus - Simple publish/subscribe event bus.
- Hermes - Fast and reliable message broker built on top of Kafka.
- JeroMQ - Implementation of ZeroMQ.
- Nakadi - Provides a RESTful API on top of Kafka.
- RabbitMQ Java client - RabbitMQ client.
- Smack - Cross-platform XMPP client library.
- NATS client - NATS client.

### Microservice

Tools for creating and managing microservices.

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

### Miscellaneous

Everything else.

- AWS SDK for Java 2.0 - Wrapper around AWS’ API.
- CQEngine - Ultra-fast, SQL-like queries on Java collections.
- Design Patterns - Implementation and explanation of the most common design patterns.
- FF4J - Feature Flags for Java.
- FizzBuzz Enterprise Edition - No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)
- IP2Location.io Java SDK - Wrapper for the IP2Location.io Geolocation API and the IP2WHOIS domain WHOIS API.
- J2ObjC - Java-to-Objective-C translator for porting Android libraries to iOS.
- JBake - Static website generator.
- JBot - Framework for building chatbots. (GPL-3.0-only)
- JCuda - JCuda offers Java bindings for CUDA and CUDA-related libraries.
- Jimfs - In-memory file system.
- JObfuscator - Source code obfuscator.
- 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.
- JPad - Snippet runner.
- jsweet - Source transpiler to TypeScript/JavaScript.
- Maven Wrapper - Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.
- Membrane Service Proxy - Open-source, reverse-proxy framework.
- MinimalFTP - Lightweight, small and customizable FTP server.
- LittleProxy - High performance HTTP proxy atop Netty’s event-based networking library.
- Modern Java - A Guide to Java 8 - Popular Java 8 guide.
- Modernizer - Detect uses of legacy Java APIs.
- OctoLinker - Browser extension which allows to navigate through code on GitHub more efficiently.
- OpenRefine - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
- PipelinR - Small utility library for using handlers and commands with pipelines.
- Polyglot for Maven - Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.
- RR4J - RR4J is a tool that records java bytecode execution and later allows developers to replay locally.
- Simple Java Mail - Mailing with a clean and fluent API.
- Smooks - Framework for fragment-based message processing. (Apache-2.0 OR LGPL-3.0-or-later)
- Svix - Library for the Svix API to send webhooks and verify signatures.
- Togglz - Implementation of the Feature Toggles pattern.
- TypeTools - Tools for resolving generic types.
- XMLBeam - Processes XML by using annotations or XPath within code.
- yGuard - Obfuscation via renaming and shrinking.

### Mobile Development

Tools for creating or managing mobile applications.

- 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.

### Monitoring

Tools that observe/monitor applications in production by providing telemetry.

- Automon - Combines the power of AOP with monitoring and/or logging tools.
- Datadog - Modern monitoring & analytics.
- Dropwizard Metrics - Expose metrics via JMX or HTTP and send them to a database.
- Failsafe Actuator - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
- Glowroot - Open-source Java APM.
- HertzBeat - Real-time monitoring system with custom-monitor and agentless.
- hippo4j - Dynamic and observable thread pool framework.
- 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.
- Instrumental - Real-time Java application performance monitoring. A commercial service with free development accounts.
- Jaeger client - Jaeger client.
- JavaMelody - Performance monitoring and profiling.
- jmxtrans - Connect to multiple JVMs and query them for their attributes via JMX. Its query language is based on JSON, which allows non-Java programmers to access the JVM attributes. Supports different output writes, including Graphite, Ganglia, and StatsD.
- Jolokia - JMX over REST.
- Micrometer - Vendor-neutral metrics/observability facade for the most popular metrics/observability libraries.
- Micrometer Tracing - Vendor-neutral distributed tracing facade for the most popular tracer libraries.
- nudge4j - Remote developer console from the browser for Java 8 via bytecode injection.
- Pinpoint - Open-source APM tool.
- Prometheus - Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.
- Sentry - Integration with Sentry, an application error tracking and performance analysis platform.
- SPM - Performance monitor with distributing transaction tracing for JVM apps.
- Stagemonitor - Open-source performance monitoring and transaction tracing for JVM apps.
- Sysmon - Lightweight platform monitoring tool for Java VMs.
- zipkin - Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures.

### Native

For working with platform-specific native libraries.

- Aparapi - Converts bytecode to OpenCL which allows execution on GPUs.
- JavaCPP - Provides efficient and easy access to native C++.
- JNA - Work with native libraries without writing JNI. Also provides interfaces to common system libraries.
- JNR - Work with native libraries without writing JNI. Also provides interfaces to common system libraries. Same goals as JNA, but faster, and serves as the basis for the upcoming Project Panama.

### Natural Language Processing

Libraries that specialize in processing text.

- 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)
- 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.

### Networking

Libraries for building network servers.

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

### ORM

APIs that handle the persistence of objects.

- Apache Cayenne - Provides a clean, static API for data access. Also includes a GUI Modeler for working with database mappings, and DB reverse engineering and generation.
- Doma - Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.
- Ebean - Provides simple and fast data access.
- EclipseLink - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
- Hibernate - Robust and widely used, with an active community. (LGPL-2.1-only)
- MyBatis - Couples objects with stored procedures or SQL statements.
- ObjectiveSql - ActiveRecord ORM for rapid development and convention over configuration.
- Permazen - Language-natural persistence layer.
- SimpleFlatMapper - Simple database and CSV mapper.

### PaaS

Java platform as a service.

- AWS Elastic Beanstalk - AWS-based, with support for Tomcat and Jetty.
- AWS Lambda - Serverless computation.
- Google Cloud - Google’s cloud infrastructure.
- Heroku - Abstract computing environments.
- Microsoft Azure - Microsoft’s cloud infrastructure.
- OpenShift - Provides additionally an on-premise solution.

### PDF

Tools to help with PDF files.

- Apache FOP - Creates PDFs from XSL-FO.
- Apache PDFBox - Toolbox for creating and manipulating PDFs.
- Dynamic Jasper - Abstraction layer to JasperReports. (LGPL-3.0-only)
- DynamicReports - Simplifies JasperReports. (LGPL-3.0-only)
- 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)
- iText - Creates PDF files programmatically.
- 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)
- Tabula - Extracts tables from PDF files.

### Performance analysis

Tools for performance analysis, profiling and benchmarking.

- fastThread - Analyze and visualize thread dumps with a free cloud-based upload interface.
- GCeasy - Tool to analyze and visualize GC logs. It provides a free cloud-based upload interface.
- 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

Frameworks that are suites of multiple libraries encompassing several categories.

#### Apache Commons

- BCEL - Byte Code Engineering Library - analyze, create, and manipulate Java class files.
- BeanUtils - Easy-to-use wrappers around the Java reflection and introspection APIs.
- BeanUtils2 - Redesign of Commons BeanUtils.
- BSF - Bean Scripting Framework - interface to scripting languages, including JSR-223.
- Chain - Chain of Responsibility pattern implementation.
- ClassScan - Find Class interfaces, methods, fields, and annotations without loading.
- CLI - Command-line arguments parser.
- CLI2 - Redesign of Commons CLI.
- Codec - General encoding/decoding algorithms, e.g. phonetic, base64 or URL.
- Collections - Extends or augments the Java Collections Framework.
- Compress - Defines an API for working with tar, zip and bzip2 files.
- Configuration - Reading of configuration/preferences files in various formats.
- Convert - Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another.
- CSV - Component for reading and writing comma separated value files.
- Daemon - Alternative invocation mechanism for unix-daemon-like java code.
- DBCP - Database connection pooling services.
- DbUtils - JDBC helper library.
- Digester - XML-to-Java-object mapping utility.
- Email - Library for sending e-mail from Java.
- Exec - API for dealing with external process execution and environment management in Java.
- FileUpload - File upload capability for your servlets and web applications.
- Finder - Java library inspired by the UNIX find command.
- Flatfile - Java library for working with flat data structures.
- Functor - Function that can be manipulated as an object, or an object representing a single, generic function.
- 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.
- Logging - Wrapper around a variety of logging API implementations.
- Math - Lightweight, self-contained mathematics and statistics components.
- Monitoring - Monitoring aims to provide a simple but extensible monitoring solution for Java applications.
- Nabla - Nabla provides automatic differentiation classes that can generate derivative of any function implemented in the Java language.
- Net - 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.
- 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.
- 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.

#### Other

- 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.
- Orienteer - Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.
- Spring - Provides many packages for dependency injection, aspect-oriented programming, security, etc.

### Processes

Libraries that help the management of operating system 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.

### Reactive libraries

Libraries for developing reactive applications.

- Akka - Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.
- Reactive Streams - Provides a standard for asynchronous stream processing with non-blocking backpressure.
- Reactor - Library for building reactive fast-data applications.
- RxJava - Allows for composing asynchronous and event-based programs using observable sequences.
- vert.x - Polyglot event-driven application framework.

### REST Frameworks

Frameworks specifically for creating RESTful services.

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

### Science

Libraries for scientific computing, analysis and visualization.

- BioJava - Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.
- Chart-FX - Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets.
- 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.
- 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.
- LogicNG - Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas.
- Mines Java Toolkit - Library for geophysical scientific computation, visualization and digital signal analysis.
- Morpheus - Provides a versatile two-dimensional memory efficient tabular data structure called a DataFrame to enable efficient in-memory analytics for scientific computing on the JVM.
- Orekit - A low level space flight dynamics library providing basic elements (orbits, dates, attitude, frames…) and various algorithms (conversions, propagations, pointing…) to handle them.
- Orson-Charts - Generates a wide variety of 3D charts that can be displayed with Swing and JavaFX or exported to PDF, SVG, PNG and JPEG. (GPL-3.0-only)
- Tablesaw - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.
- XChart - Light-weight library for plotting data. Many customizable chart types are available.

### Search

Engines that index documents for search and analysis.

- 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.
- Indexer4j - Simple and light full text indexing and searching library.

### Security

Libraries that handle security, authentication, authorization or session management.

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

### Serialization

Libraries that handle serialization with high efficiency.

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

### Server

Servers specifically used to deploy applications.

- 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.
- nanohttpd - Tiny, easily embeddable HTTP server.
- WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)

### Template Engine

Tools that substitute expressions in a template.

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

### Testing

Tools that test from model to the view.

#### Asynchronous

Tools that simplify testing asynchronous services.

- Awaitility - DSL for synchronizing asynchronous operations.
- 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.
- Karate - DSL that combines API test-automation, mocks and performance-testing making testing REST/HTTP services easy.
- REST Assured - DSL for easy testing of REST/HTTP services.
- WebTau - Test across REST-API, Graph QL, Browser, Database, CLI and Business Logic with consistent set of matchers and concepts.

#### BDD

Testing for the software development process that emerged from TDD and was heavily influenced by DDD and OOAD.

- 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.
- JBehave - Extensively configurable framework that describes stories.
- JGiven - Provides a fluent API which allows for simpler composition.
- Lamdba Behave - Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.
- Serenity BDD - Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.

#### Fixtures

Everything related to the creation and handling of random data.

- Beanmother - Sets up beans from YAML fixtures.
- Datafaker - Modern fake data generator forked from Java Faker.
- Fixture Factory - Generates fake objects from a template.
- jFairy - Fake data generator.
- Instancio - Automates data setup in unit tests by generating fully-populated, reproducible objects. Includes JUnit 5 extension.
- Randomized Testing - JUnit test runner and plugins for running JUnit tests with pseudo-randomness.
- Java Faker - Port of Ruby’s fake data generator.
- Mockneat - Another fake data generator.

#### Frameworks

Provide environments to run tests for a specific use case.

- ArchUnit - Test library for specifying and asserting architecture rules.
- Apache JMeter - Functional testing and performance measurements.
- Arquillian - Integration and functional testing platform for Java EE containers.
- Citrus - Integration testing framework that focuses on both client- and server-side messaging.
- Gatling - Load testing tool designed for ease of use, maintainability and high performance.
- JUnit - Common testing framework.
- jqwik - Engine for property-based testing built on JUnit 5.
- Pact JVM - Consumer-driven contract testing.
- PIT - Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.

#### Matchers

Libraries that provide custom matchers.

- AssertJ - Fluent assertions that improve readability.
- Hamcrest - Matchers that can be combined to create flexible expressions of intent.
- JSONAssert - Simplifies testing JSON strings.
- JsonUnit - Library that simplifies JSON comparison in tests.
- Truth - Google’s fluent assertion and proposition framework.
- XMLUnit - Simplifies testing for XML output.

#### Miscellaneous

Other stuff related to testing.

- ConsoleCaptor - Captures console output for unit testing purposes.
- junit-dataprovider - TestNG-like data provider/runner for JUnit.
- LogCaptor - Captures log entries for unit testing purposes.
- log-capture - Captures log entries and provides assertions for unit and integration testing.
- Mutability Detector - Reports whether instances of a given class are immutable.
- pojo-tester - Automatically performs tests on basic POJO methods. (LGPL-3.0-only)
- raml-tester - Tests if a request/response matches a given RAML definition.
- Selfie - Snapshot testing (inline and on disk).
- TestContainers - Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

#### Mocking

Tools which mock collaborators to help testing single, isolated units.

- JMockit - Integration testing, API mocking and faking, and code coverage.
- Mockito - Mocking framework that lets you write tests with a clean and simple API.
- MockServer - Allows mocking of systems integrated with HTTPS.
- Moco - Concise web services for stubs and mocks.
- PowerMock - Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.
- WireMock - Stubs and mocks web services.
- EasyMock - EasyMock is a Java library that provides an easy way to use Mock Objects in unit testing.

### Utility

Libraries which provide general utility functions.

- Arthas - Allows to troubleshoot production issues for applications without modifying code or restarting servers.
- bucket4j - Rate limiting library based on token-bucket algorithm.
- cactoos - Collection of object-oriented primitives.
- Chocotea - Generates postman collection, environment and integration tests from java code.
- 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.
- dregex - Regular expression engine that uses deterministic finite automata. It supports some Perl-style features and yet retains linear matching time, and also offers set operations.
- Embulk - Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.
- fswatch - Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.
- Gephi - Cross-platform for visualizing and manipulating large graph networks. (GPL-3.0-only)
- Guava - Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.
- JADE - Framework and environment for building and debugging multi-agent systems. (LGPL-2.0-only)
- 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.

### Version Managers

Utilities that help create the development shell environment and switch between different Java versions.

- 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.

### Web Crawling

Libraries that analyze the content of websites.

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

### Web Frameworks

Frameworks that handle the communication between the layers of a web application.

- 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.
- Blade - Lightweight, modular framework that aims to be elegant and simple.
- Bootique - Minimally opinionated framework for runnable apps.
- Firefly - Asynchronous framework for rapid development of high-performance web application.
- Javalin - Microframework for web applications.
- 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.
- Takes - Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.
- Vaadin - Event-driven framework that uses standard web components. Server-side architecture with Ajax on the client side.

### Workflow Orchestration Engines

- 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.

## Resources

### Related Awesome Lists

Awesome Lists related to the Java & JVM ecosystem.

- Awesome Annotation Processing
- Awesome Graal
- Awesome Gradle Plugins
- AwesomeJavaFX
- Awesome JVM
- Awesome Microservices
- Awesome REST
- Awesome Selenium
- Awesome Hybris
- ciandcd
- Useful Java Links
- Java Concurrency Checklist
- Java Developer Roadmap

### Communities

Active discussions.

- r/java - Subreddit for the Java community.
- Stack Overflow - Question/answer platform.

### Frontends

Websites that provide a frontend for this list. Please note, there won’t be an official website. We don’t associate with a particular website and everybody is allowed to create one.

- java.libhunt.com

### Influential Books

Books that made a big impact and are still worth reading.

- Core Java Volume I–Fundamentals
- Core Java, Volume II–Advanced Features
- Effective Java (3rd Edition)
- Head First Java (3rd Edition)
- Java Concurrency in Practice
- The Well-Grounded Java Developer (2nd Edition)
- Thinking in Java

### Podcasts and Screencasts

Something to look at or listen to while programming.

- 140 Second Ducklings - Short videos on Twitter explaining Java debugging in depth.
- A Bootiful Podcast
- Foojay Podcast
- Inside Java (Official)
- Java Off Heap
- The Java Posse - Discontinued as of 02/2015.

### People

#### Twitter

Active accounts to follow. Descriptions from Twitter.

- Adam Bien - Freelance author, JavaOne Rockstar speaker, consultant, Java Champion.
- Aleksey Shipilëv - Performance geek, benchmarking czar, concurrency bug hunter.
- Antonio Goncalves - Java Champion, JUG Leader, Devoxx France, Java EE 6/7, JCP, Author.
- Arun Gupta - Java Champion, JavaOne Rockstar, JUG Leader, Devoxx4Kids-er, VP of Developer Advocacy at Couchbase.
- Brian Goetz - Java Language Architect at Oracle.
- Bruno Borges - Product Manager/Java Jock at Oracle.
- Chris Engelbert - Open Source Enthusiast, Speaker, Developer, Developer Advocacy at TimescaleDB.
- Chris Richardson - Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, *POJOs in Action- author.
- Ed Burns - Consulting Member of the Technical Staff at Oracle.
- Eugen Paraschiv - Author of the Spring Security Course.
- Heinz Kabutz - Java Champion, speaker, author of The Java Specialists’ Newsletter, concurrency performance expert.
- Holly Cummins - Technical Lead of IBM London’s Bluemix Garage, Java Champion, developer, author, JavaOne rockstar.
- James Weaver - Java/JavaFX/IoT developer, author and speaker.
- Java EE - Official Java EE Twitter account.
- Java Magazine - Official Java Magazine account.
- Java - Official Java Twitter account.
- Javin Paul - Well-known Java blogger.
- Josh Long - Spring Advocate at Pivotal, author of O’Reilly’s Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star.
- Lukas Eder - Java Champion, speaker, Founder and CEO Data Geekery (jOOQ).
- Mani Sarkar - Java champion, Polyglot, Software Crafter involved with @graalvm, AI/ML/DL, Data Science, Developer communities, speaker & blogger. Creator of couple of awesome lists like this one.
- Mario Fusco - RedHatter, JUG coordinator, frequent speaker and author.
- Mark Heckler - Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud.
- Mark Reinhold - Chief Architect, Java Platform Group, Oracle.
- Markus Eisele - Java EE evangelist, Red Hat.
- Martijn Verburg - London JUG co-leader, speaker, author, Java Champion and much more.
- Martin Thompson - Pasty faced performance gangster.
- Monica Beckwith - Performance consultant, JavaOne Rock Star.
- OpenJDK - Official OpenJDK account.
- Peter Lawrey - Peter Lawrey, Java performance expert.
- Randy Shoup - Stitch Fix VP Engineering, speaker, JavaOne Rock Star.
- Reza Rahman - Java EE/GlassFish/WebLogic evangelist, author, speaker, open source hacker.
- Sander Mak - Java Champion, author.
- Simon Maple - Java Champion, VirtualJUG founder, LJC leader, RebelLabs author.
- Spencer Gibb - Software Engineer, Dad, Geek, Co-founder and Lead of Spring Cloud Core @pivotal.
- Stephen Colebourne - Java Champion, speaker.
- Trisha Gee - Java Champion and speaker.
- Venkat Subramaniam - Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion.
- Vlad Mihalcea - Java Champion working on Hypersistence Optimizer, database aficionado, author of High-Performance Java Persistence book.

#### Other

- Groundbreakers - Oracle ACEs, Groundbreaker Ambassadors and Java Champions.

### Websites

Sites to read.

- Baeldung
- Dzone
- foojay.io
- Google Java Style
- InfoQ
- Java Algorithms and Clients
- Java, SQL, and jOOQ
- Java.net
- Javalobby
- JavaWorld
- JAXenter
- RebelLabs
- OverOps Blog
- TheServerSide.com
- Vanilla Java
- Voxxed
- Java Weekly

## Contributing

Contributions are very welcome!

Please have a look at the CONTRIBUTING guidelines and the validation tools.