Awesome Java

这是Github上关于Java相关的工具，框架等等资源集合. 原文参考: https://github.com/akullpp/awesome-java。 @pdai

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

Bean Mapping

Frameworks that ease bean mapping.

• Dozer (opens new window) - Mapper that copies data from one object to another using annotations and API or XML configuration.
• JMapper (opens new window) - Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.
• MapStruct (opens new window) - Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.
• ModelMapper (opens new window) - Intelligent object mapping library that automatically maps objects to each other.
• Orika (opens new window) - JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.
• Selma (opens new window) - Annotation processor-based bean mapper.

Build

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

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

Bytecode Manipulation

Libraries to manipulate bytecode programmatically.

• ASM (opens new window) - All-purpose, low-level bytecode manipulation and analysis.
• Byte Buddy (opens new window) - Further simplifies bytecode generation with a fluent API.
• bytecode-viewer (opens new window) - Java 8 Jar & Android APK reverse engineering suite.
• Byteman (opens new window) - Manipulate bytecode at runtime via DSL (rules); mainly for testing/troubleshooting.
• cglib (opens new window) - Bytecode generation library.
• Javassist (opens new window) - Tries to simplify bytecode editing.
• Mixin (opens new window) - Manipulate bytecode at runtime using real Java code.

Caching

Libraries that provide caching facilities.

• Caffeine (opens new window) - High-performance, near-optimal caching library.
• Ehcache (opens new window) - Distributed general-purpose cache.
• Infinispan (opens new window) - Highly concurrent key/value datastore used for caching.

CLI

Libraries for everything related to the CLI.

• ASCII Table (opens new window) - Library to draw tables in ASCII.
• Airline (opens new window) - Annotation-based framework for parsing Git-like command-line arguments.
• args4j (opens new window) - Small library to parse command-line arguments.
• Jansi (opens new window) - ANSI escape codes to format console output.
• Java ASCII Render (opens new window) - Graphical primitives for the console.
• JCommander (opens new window) - Command-line argument-parsing framework with custom types and validation via implementing interfaces.
• JLine (opens new window) - Includes features from modern shells like completion or history.
• JOpt Simple (opens new window) - Fluent parser that uses the POSIX#getopt and GNU#getopt_long syntaxes.
• picocli (opens new window) - ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.
• Text-IO (opens new window) - Aids the creation of full console-based applications.
• Lanterna (opens new window) - Easy console text-GUI library, similar to curses.

Cluster Management

Frameworks that can dynamically manage applications inside of a cluster.

• Apache Aurora (opens new window) - Mesos framework for long-running services and cron jobs.
• Apache Mesos (opens new window) - Abstracts CPU, memory, storage, and other compute resources away from machines.
• Singularity (opens new window) - 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 (opens new window) - Static analysis of coding conventions and standards.
• Error Prone (opens new window) - Catches common programming mistakes as compile-time errors.
• Infer (opens new window) - Modern static analysis tool for verifying the correctness of code.
• jQAssistant (opens new window) - Static code analysis with Neo4J-based query language.
• NullAway (opens new window) - Eliminates NullPointerExceptions with low build-time overhead.
• PMD (opens new window) - Source code analysis for finding bad coding practices.
• SonarJava (opens new window) - Static analyzer for SonarQube & SonarLint.
• Sourcetrail (opens new window) - Visual source code navigator.
• Spoon (opens new window) - Library for analyzing and transforming Java source code.
• Spotbugs (opens new window) - Static analysis of bytecode to find potential bugs.

Code Coverage

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

• Clover (opens new window) - Relies on source-code instrumentation instead of bytecode instrumentation.
• Cobertura (opens new window) - Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics.
• JaCoCo (opens new window) - 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 (opens new window) - JSR-269 code generator for algebraic data types.
• Auto (opens new window) - Generates factory, service, and value classes.
• FreeBuilder (opens new window) - Automatically generates the Builder pattern.
• Immutables (opens new window) - Annotation processors to generate simple, safe and consistent value objects.
• JavaPoet (opens new window) - API to generate source files.
• JHipster (opens new window) - Yeoman source code generator for Spring Boot and AngularJS.
• Joda-Beans (opens new window) - Small framework that adds queryable properties to Java, enhancing JavaBeans.
• Lombok (opens new window) - Code generator that aims to reduce verbosity.

Compiler-compiler

Frameworks that help to create parsers, interpreters or compilers.

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

Configuration

Libraries that provide external configuration.

• centraldogma (opens new window) - Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.
• cfg4j (opens new window) - Modern configuration library for distributed apps written in Java.
• config (opens new window) - Configuration library for JVM languages.
• dotenv (opens new window) - A twelve-factor configuration library for Java.
• ini4j (opens new window) - Provides an API for handling Windows' INI files.
• KAConf (opens new window) - Annotation-based configuration system for Java and Kotlin.
• owner (opens new window) - Reduces boilerplate of properties.

Constraint Satisfaction Problem Solver

Libraries that help with implementing optimization and satisfiability problems.

• Choco (opens new window) - Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques.
• JaCoP (opens new window) - Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models.
• OptaPlanner (opens new window) - Business planning and resource scheduling optimization solver.

CSV

Frameworks and libraries that simplify reading/writing CSV data.

• jackson-dataformat-csv (opens new window) - Jackson extension for reading and writing CSV.
• opencsv (opens new window) - Simple CSV parser.
• Super CSV (opens new window) - Powerful CSV parser with support for Dozer, Joda-Time and Java 8.
• uniVocity-parsers (opens new window) - One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.

Database

Everything that simplifies interactions with the database.

• Apache Phoenix (opens new window) - High-performance relational database layer over HBase for low-latency applications.
• Chronicle Map (opens new window) - Efficient, in-memory (opt. persisted to disk), off-heap key-value store.
• druid (opens new window) - High-performance, column-oriented, distributed data store.
• eXist (opens new window) - A NoSQL document database and application platform.
• FlexyPool (opens new window) - Brings metrics and failover strategies to the most common connection pooling solutions.
• Flyway (opens new window) - Simple database migration tool.
• H2 (opens new window) - Small SQL database notable for its in-memory functionality.
• HikariCP (opens new window) - High-performance JDBC connection pool.
• jasync-sql (opens new window) - Async DB driver for MySQL and PostgreSQL.
• JDBI (opens new window) - Convenient abstraction of JDBC.
• Jedis (opens new window) - Small client for interaction with Redis, with methods for commands.
• Jest (opens new window) - Client for the Elasticsearch REST API.
• jetcd (opens new window) - Client library for etcd.
• Jinq (opens new window) - Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ).
• jOOQ (opens new window) - Generates typesafe code based on SQL schema.
• Liquibase (opens new window) - Database-independent library for tracking, managing and applying database schema changes.
• MapDB (opens new window) - Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.
• MariaDB4j (opens new window) - Launcher for MariaDB that requires no installation or external dependencies.
• OrientDB (opens new window) - Embeddable distributed database written on top of Hazelcast.
• Presto (opens new window) - Distributed SQL query engine for big data.
• Querydsl (opens new window) - Typesafe unified queries.
• Realm (opens new window) - Mobile database to run directly inside phones, tablets or wearables.
• Redisson (opens new window) - Allows for distributed and scalable data structures on top of a Redis server.
• requery (opens new window) - A 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 (opens new window) - Database access library that utilizes Java 8's Stream API for querying.
• sql2o (opens new window) - Thin JDBC wrapper that simplifies database access and provides simple mapping of ResultSets to POJOs.
• Vibur DBCP (opens new window) - JDBC connection pool library with advanced performance monitoring capabilities.
• Xodus (opens new window) - Highly concurrent transactional schema-less and ACID-compliant embedded database.

Data Structures

Efficient and specific data structures.

• Apache Avro (opens new window) - Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.
• Apache Orc (opens new window) - Fast and efficient columnar storage format for Hadoop-based workloads.
• Apache Parquet (opens new window) - Columnar storage format based on assembly algorithms from Google's paper on Dremel.
• Apache Thrift (opens new window) - Data interchange format that originated at Facebook.
• Big Queue (opens new window) - A big, fast and persistent queue based on memory-mapped files.
• Persistent Collection (opens new window) - Persistent and immutable analogue of the Java Collections Framework.
• Protobuf (opens new window) - Google's data interchange format.
• SBE (opens new window) - Simple Binary Encoding, one of the fastest message formats around.
• Tape (opens new window) - A lightning-fast, transactional, file-based FIFO.
• Wire (opens new window) - Clean, lightweight protocol buffers.

Date and Time

Libraries related to handling date and time.

• Almanac Converter (opens new window) - Simple conversion between different calendar systems.
• iCal4j (opens new window) - Parse and build iCalendar RFC 5545 (opens new window) data models.
• ThreeTen-Extra (opens new window) - Additional date-time classes that complement those in JDK 8.
• Time4J (opens new window) - Advanced date and time library.

Dependency Injection

Libraries that help to realize the Inversion of Control (opens new window) paradigm.

• Apache DeltaSpike (opens new window) - CDI extension framework.
• Dagger2 (opens new window) - Compile-time injection framework without reflection.
• Feather (opens new window) - Ultra-lightweight, JSR-330-compliant dependency injection library.
• Governator (opens new window) - Extensions and utilities that enhance Google Guice.
• Guice (opens new window) - Lightweight and opinionated framework that completes Dagger.
• HK2 (opens new window) - Lightweight and dynamic dependency injection framework.

Development

Augmentation of the development process at a fundamental level.

• AspectJ (opens new window) - Seamless aspect-oriented programming extension.
• DCEVM (opens new window) - JVM modification that allows unlimited redefinition of loaded classes at runtime.
• Faux Pas (opens new window) - 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 (opens new window) - Unlimited runtime class and resource redefinition.
• JavaParser (opens new window) - Parse, modify and generate Java code.
• JavaSymbolSolver (opens new window) - A symbol solver for Java.
• JRebel (opens new window) - Instantly reloads code and configuration changes without redeploys.
• NoException (opens new window) - Allows checked exceptions in functional interfaces and converts exceptions to Optional return.

Distributed Applications

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

• Apache Geode (opens new window) - In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.
• Apache Storm (opens new window) - Realtime computation system.
• Apache ZooKeeper (opens new window) - Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.
• Atomix (opens new window) - Fault-tolerant distributed coordination framework.
• Axon Framework (opens new window) - Framework for creating CQRS applications.
• Dropwizard Circuit Breaker (opens new window) - Circuit breaker design pattern for Dropwizard.
• Failsafe (opens new window) - Simple failure handling with retries and circuit breakers.
• Hazelcast (opens new window) - Highly scalable in-memory datagrid with a free open-source version.
• Hystrix (opens new window) - Provides latency and fault tolerance.
• JGroups (opens new window) - Toolkit for reliable messaging and cluster creation.
• Orbit (opens new window) - Virtual actors; adds another level of abstraction to traditional actors.
• Quasar (opens new window) - Lightweight threads and actors for the JVM.
• resilience4j (opens new window) - Functional fault tolerance library.
• ScaleCube (opens new window) - Embeddable Cluster-Membership library based on SWIM and gossip protocol.
• Zuul (opens new window) - A 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 (opens new window) - Provides transactions for REST, SOA and microservices with support for JTA and XA.
• Bitronix (opens new window) - A simple but complete implementation of the JTA 1.1 API.
• Narayana (opens new window) - Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards.

Distribution

Tools that handle the distribution of applications in native formats.

• Bintray (opens new window) - Version control for binaries that handle publishing. Compatible with Maven or Gradle, with a free plan for open-source software as well as several business plans.
• Boxfuse (opens new window) - Deployment of JVM applications to AWS using the principles of immutable infrastructure.
• Capsule (opens new window) - Simple and powerful packaging and deployment. A fat JAR on steroids, or a "Docker for Java" that supports JVM-optimized containers.
• Central Repository (opens new window) - 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.
• IzPack (opens new window) - Setup authoring tool for cross-platform deployments.
• JitPack (opens new window) - Easy-to-use package repository for GitHub. Builds Maven/Gradle projects on demand and publishes ready-to-use packages.
• Nexus (opens new window) - Binary management with proxy and caching capabilities.
• packr (opens new window) - Packs JARs, assets and the JVM for native distribution on Windows, Linux and Mac OS X.
• really-executable-jars-maven-plugin (opens new window) - Maven plugin for making self-executing JARs.

Document Processing

Libraries that assist with processing office document formats.

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

Formal Verification

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

• CATG (opens new window) - Concolic unit testing engine. Automatically generates unit tests using formal methods.
• Checker Framework (opens new window) - Pluggable type systems. Includes nullness types, physical units, immutability types and more.
• Daikon (opens new window) - Detects likely program invariants and generates JML specs based on those invariants.
• Java Path Finder (JPF) (opens new window) - JVM formal verification tool containing a model checker and more. Created by NASA.
• JMLOK 2.0 (opens new window) - Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected.
• KeY (opens new window) - 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.
• OpenJML (opens new window) - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers.

Functional Programming

Libraries that facilitate functional programming.

• cyclops-react (opens new window) - Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.
• derive4j (opens new window) - Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms.
• Fugue (opens new window) - Functional extensions to Guava.
• Functional Java (opens new window) - Implements numerous basic and advanced programming abstractions that assist composition-oriented development.
• jOOλ (opens new window) - 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 (opens new window) - Collection of stream utilities.
• StreamEx (opens new window) - Enhances Java 8 Streams.
• Vavr (opens new window) - Functional component library that provides persistent data types and functional control structures.

Game Development

Frameworks that support the development of games.

• FXGL (opens new window) - JavaFX Game Development Framework.
• jMonkeyEngine (opens new window) - Game engine for modern 3D development.
• libGDX (opens new window) - All-round cross-platform, high-level framework.
• LWJGL (opens new window) - Robust framework that abstracts libraries like OpenGL/CL/AL.

Geospatial

Libraries for working with geospatial data and algorithms.

• Apache SIS (opens new window) - Library for developing geospatial applications.
• Geo (opens new window) - GeoHash utilities in Java.
• Geotoolkit.org (opens new window) - Library for developing geospatial applications. Built on top of the Apache SIS project.
• GeoTools (opens new window) - Library that provides tools for geospatial data.
• GraphHopper (opens new window) - Road-routing engine. Used as a Java library or standalone web service.
• H2GIS (opens new window) - A spatial extension of the H2 database.
• Jgeohash (opens new window) - Library for using the GeoHash algorithm.
• Mapsforge (opens new window) - Map rendering based on OpenStreetMap data.
• Spatial4j (opens new window) - General-purpose spatial/geospatial library.

GUI

Libraries to create modern graphical user interfaces.

• JavaFX (opens new window) - The successor of Swing.
• Scene Builder (opens new window) - Visual layout tool for JavaFX applications.
• SWT (opens new window) - The Standard Widget Toolkit, a graphical widget toolkit.

High Performance

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

• Agrona (opens new window) - Data structures and utility methods that are common in high-performance applications.
• Disruptor (opens new window) - Inter-thread messaging library.
• Eclipse Collections (opens new window) - Collections framework inspired by Smalltalk.
• fastutil (opens new window) - Fast and compact type-specific collections.
• HPPC (opens new window) - Primitive collections.
• JCTools (opens new window) - Concurrency tools currently missing from the JDK.
• Koloboke (opens new window) - Hash sets and hash maps.

HTTP Clients

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

• Async Http Client (opens new window) - Asynchronous HTTP and WebSocket client library.
• Feign (opens new window) - HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.
• OkHttp (opens new window) - HTTP+SPDY client.
• Play WS (opens new window) - Typesafe client with reactive streams and caching.
• restQL-core (opens new window) - Microservice query language that fetches information from multiple services.
• Retrofit (opens new window) - Typesafe REST client.
• Ribbon (opens new window) - Client-side IPC library that is battle-tested in cloud.
• Riptide (opens new window) - Client-side response routing for Spring's RestTemplate.

Hypermedia Types

Libraries that handle serialization to hypermedia types.

• JSON-LD (opens new window) - JSON-LD implementation.
• Siren4J (opens new window) - Library for the Siren specification.

IDE

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

• Eclipse (opens new window) - Established open-source project with support for lots of plugins and languages.
• IntelliJ IDEA (opens new window) - Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.
• NetBeans (opens new window) - Provides integration for several Java SE and EE features, from database access to HTML5.
• Visual Studio Code (opens new window) - 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 (opens new window) - Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.
• Tess4J (opens new window) - A JNA wrapper for Tesseract OCR API.
• Thumbnailator (opens new window) - High-quality thumbnail generation library.
• TwelveMonkeys (opens new window) - Collection of plugins that extend the number of supported image file formats.
• ZXing (opens new window) - Multi-format 1D/2D barcode image processing library.

JSON

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

• DSL-JSON (opens new window) - JSON library with advanced compile time databinding.
• Genson (opens new window) - Powerful and easy-to-use Java-to-JSON conversion library.
• Gson (opens new window) - Serializes objects to JSON and vice versa. Good performance with on-the-fly usage.
• HikariJSON (opens new window) - High-performance JSON parser, 2x faster than Jackson.
• jackson-modules-java8 (opens new window) - Set of Jackson modules for Java 8 datatypes and features.
• Jackson-datatype-money (opens new window) - Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types.
• Jackson (opens new window) - Similar to GSON, but offers performance gains if you need to instantiate the library more often.
• JSON-io (opens new window) - Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer.
• jsoniter (opens new window) - Fast and flexible library with iterator and lazy parsing API.
• LoganSquare (opens new window) - JSON parsing and serializing library based on Jackson's streaming API. Outperforms GSON & Jackson's library.
• Moshi (opens new window) - Modern JSON library, less opinionated and uses built-in types like List and Map.
• Yasson (opens new window) - Binding layer between classes and JSON documents similar to JAXB.

JSON Processing

Libraries for processing data in JSON format.

• fastjson (opens new window) - Very fast processor with no additional dependencies and full data binding.
• Jolt (opens new window) - JSON to JSON transformation tool.
• JsonPath (opens new window) - Extract data from JSON using XPATH-like syntax.
• JsonSurfer (opens new window) - Streaming JsonPath processor dedicated to processing big and complicated JSON data.

JVM and JDK

Current implementations of the JVM/JDK.

• Avian (opens new window) - JVM with both JIT and AOT modes. Includes an iOS port.
• Graal (opens new window) - Polyglot virtual machine which can be embedded.
• OpenJ9 (opens new window) - High performance, enterprise calibre, flexibly licensed, openly governed cross platform Java Virtual Machine extending and augmenting the runtime technology components from the Eclipse OMR and OpenJDK project.
• OpenJDK (opens new window) - Open-source implementation for Linux.
• ParparVM (opens new window) - VM with non-blocking, concurrent GC for iOS.
• Zulu (opens new window) - OpenJDK builds for Windows, Linux, and Mac OS X.

Logging

Libraries that log the behavior of an application.

• Apache Log4j 2 (opens new window) - Complete rewrite with a powerful plugin and configuration architecture.
• Graylog (opens new window) - Open-source aggregator suited for extended role and permission management.
• Kibana (opens new window) - Analyzes and visualizes log files. Some features require payment.
• Logback (opens new window) - Robust logging library with interesting configuration options via Groovy.
• Logbook (opens new window) - Extensible, open-source library for HTTP request and response logging.
• Logstash (opens new window) - Tool for managing log files.
• SLF4J (opens new window) - Abstraction layer/simple logging facade.
• tinylog (opens new window) - Lightweight logging framework with static logger class.
• Tracer (opens new window) - Call tracing and log correlation in distributed systems.

Machine Learning

Tools that provide specific statistical algorithms for learning from data.

• Apache Flink (opens new window) - Fast, reliable, large-scale data processing engine.
• Apache Mahout (opens new window) - Scalable algorithms focused on collaborative filtering, clustering and classification.
• Apache Spark (opens new window) - Data analytics cluster-computing framework.
• DatumBox (opens new window) - Provides several algorithms and pre-trained models for natural language processing.
• DeepDive (opens new window) - Creates structured information from unstructured data and integrates it into an existing database.
• Deeplearning4j (opens new window) - Distributed and multi-threaded deep learning library.
• H2O (opens new window) - Analytics engine for statistics over big data.
• JSAT (opens new window) - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution.
• Oryx 2 (opens new window) - Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
• Smile (opens new window) - The Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.
• Weka (opens new window) - Collection of algorithms for data mining tasks ranging from pre-processing to visualization.

Messaging

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

• Aeron (opens new window) - Efficient, reliable, unicast and multicast message transport.
• Apache ActiveMQ (opens new window) - Message broker that implements JMS and converts synchronous to asynchronous communication.
• Apache Camel (opens new window) - Glues together different transport APIs via Enterprise Integration Patterns.
• Apache Kafka (opens new window) - High-throughput distributed messaging system.
• Apache Pulsar (opens new window) - Distributed pub/sub-messaging system.
• Apache RocketMQ (opens new window) - A fast, reliable, and scalable distributed messaging platform.
• EventBus (opens new window) - Simple publish/subscribe event bus.
• Hermes (opens new window) - Fast and reliable message broker built on top of Kafka.
• JeroMQ (opens new window) - Implementation of ZeroMQ.
• Nakadi (opens new window) - Provides a RESTful API on top of Kafka.
• Smack (opens new window) - Cross-platform XMPP client library.

Miscellaneous

Everything else.

• Codename One (opens new window) - Cross-platform solution for writing native mobile apps.
• CQEngine (opens new window) - Ultra-fast, SQL-like queries on Java collections.
• Design Patterns (opens new window) - Implementation and explanation of the most common design patterns.
• Failsafe (opens new window) - Simple failure handling with retries and circuit breakers.
• FF4J (opens new window) - Feature Flags for Java.
• FizzBuzz Enterprise Edition (opens new window) - No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes.
• J2ObjC (opens new window) - Java-to-Objective-C translator for porting Android libraries to iOS.
• JavaX (opens new window) - Reinventing and extending Java with a focus on simplicity.
• JBake (opens new window) - Static website generator.
• JBot (opens new window) - Framework for building chatbots.
• Jimfs (opens new window) - In-memory file system.
• Joda-Money (opens new window) - Basic currency and money classes and algorithms not provided by the JDK.
• JPad (opens new window) - Snippet runner.
• LightAdmin (opens new window) - Pluggable CRUD UI library for rapid application development.
• Maven Wrapper (opens new window) - Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.
• Membrane Service Proxy (opens new window) - An open-source, reverse-proxy framework written in Java.
• MinimalFTP (opens new window) - Lightweight, small and customizable FTP server.
• Modern Java - A Guide to Java 8 (opens new window) - Popular Java 8 guide.
• Modernizer (opens new window) - Detect uses of legacy Java APIs.
• Multi-OS Engine (opens new window) - An open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.
• OpenRefine (opens new window) - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
• Polyglot for Maven (opens new window) - Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.
• Smooks (opens new window) - Extensible framework for building applications that process data which means bindings, transformations, message processing and enrichment.
• Togglz (opens new window) - Implementation of the Feature Toggles pattern.
• TypeTools (opens new window) - Tools for resolving generic types.
• XMLBeam (opens new window) - Processes XML by using annotations or XPath within code.
• OctoLinker (opens new window) - Browser extension which allows to navigate through code on GitHub more efficiently.

Microservice

Tools for creating and managing microservices.

• Apollo (opens new window) - Libraries for writing composable microservices.
• consul-api (opens new window) - Client for the Consul (opens new window) API: a distributed, highly available and datacenter-aware registry/discovery service.
• Eureka (opens new window) - REST-based service registry for resilient load balancing and failover.
• Lagom (opens new window) - Framework for creating microservice-based systems.
• Micronaut (opens new window) - Modern full-stack framework with focus on modularity, minimal memory footprint and startup time.

Monitoring

Tools that monitor applications in production.

• AppDynamics (opens new window) - Performance monitor.
• Automon (opens new window) - Combines the power of AOP with monitoring and/or logging tools.
• BugSnag (opens new window) - Exception and error monitoring with an integration of several third party tools for a better workflow and a free hobbyist tier.
• LeakCanary (opens new window) - Memory leak detection.
• Failsafe Actuator (opens new window) - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
• Glowroot (opens new window) - Open-source Java APM.
• inspectIT (opens new window) - 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 (opens new window) - Real-time Java application performance monitoring. A commercial service with free development accounts.
• JavaMelody (opens new window) - Performance monitoring and profiling.
• jmxtrans (opens new window) - 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 (opens new window) - JMX over REST.
• Kamon (opens new window) - Tool for monitoring applications running on the JVM.
• Metrics (opens new window) - Expose metrics via JMX or HTTP and send them to a database.
• New Relic (opens new window) - Performance monitor.
• nudge4j (opens new window) - Remote developer console from the browser for Java 8 via bytecode injection.
• OverOps (opens new window) - In-production error monitoring and debugging.
• Pinpoint (opens new window) - Open-source APM tool.
• Prometheus (opens new window) - Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.
• SPM (opens new window) - Performance monitor with distributing transaction tracing for JVM apps.
• Stagemonitor (opens new window) - Open-source performance monitoring and transaction tracing for JVM apps.
• Sysmon (opens new window) - Lightweight platform monitoring tool for Java VMs.
• zipkin (opens new window) - Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures.

Native

For working with platform-specific native libraries.

• JavaCPP (opens new window) - Provides efficient and easy access to native C++.
• JNA (opens new window) - Work with native libraries without writing JNI. Also provides interfaces to common system libraries.
• JNR (opens new window) - 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 (opens new window).

Natural Language Processing

Libraries that specialize in processing text.

• CogCompNLP (opens new window) - Provides common annotators for plain text input.
• CoreNLP (opens new window) - Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis.
• DKPro (opens new window) - Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.
• LingPipe (opens new window) - Toolkit for tasks ranging from POS tagging to sentiment analysis.

Networking

Libraries for building network servers.

• Comsat (opens new window) - Integrates standard Java web-related APIs with Quasar fibers and actors.
• Dubbo (opens new window) - High-performance RPC framework.
• Finagle (opens new window) - Extensible RPC system for constructing high-concurrency servers. It implements uniform client and server APIs for several protocols, and is protocol-agnostic to simplify implementation of new protocols.
• Grizzly (opens new window) - NIO framework. Used as a network layer in Glassfish.
• gRPC (opens new window) - RPC framework based on protobuf and HTTP/2.
• KryoNet (opens new window) - Provides a clean and simple API for efficient TCP and UDP client/server network communication using NIO and Kryo.
• MINA (opens new window) - Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.
• Netty (opens new window) - Framework for building high-performance network applications.
• Nifty (opens new window) - Implementation of Thrift clients and servers on Netty.
• sshj (opens new window) - Programatically use SSH, SCP or SFTP.
• TLS Channel (opens new window) - Implements a ByteChannel interface over SSLEngine, enabling easy-to-use (socket-like) TLS.
• Undertow (opens new window) - Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly.
• urnlib (opens new window) - Represent, parse and encode URNs, as in RFC 2141.

ORM

APIs that handle the persistence of objects.

• Apache Cayenne (opens new window) - 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 (opens new window) - Provides simple and fast data access.
• EclipseLink (opens new window) - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
• Hibernate (opens new window) - Robust and widely used, with an active community.
• MyBatis (opens new window) - Couples objects with stored procedures or SQL statements.
• SimpleFlatMapper (opens new window) - Simple database and CSV mapper.

PaaS

Java platform as a service.

• AWS Elastic Beanstalk (opens new window) - AWS-based, with support for Tomcat and Jetty.
• AWS Lambda (opens new window) - Serverless computation.
• Google App Engine (opens new window) - PaaS on Google's infrastructure.
• Heroku (opens new window) - Abstract computing environments.
• Jelastic (opens new window) - Supports Tomcat, Jetty, GlassFish, JBoss, TomEE and WildFly.
• OpenShift Enterprise (opens new window) - On-premise solution.

PDF

Tools to help with PDF file creation.

• Apache FOP (opens new window) - Creates PDFs from XSL-FO.
• Apache PDFBox (opens new window) - Toolbox for creating and manipulating PDFs.
• Dynamic Jasper (opens new window) - Abstraction layer to JasperReports.
• DynamicReports (opens new window) - Simplifies JasperReports.
• flyingsaucer (opens new window) - XML/XHTML and CSS 2.1 renderer.
• iText (opens new window) - Creates PDF files programmatically.
• JasperReports (opens new window) - Complex reporting engine.

Performance analysis

Tools for performance analysis, profiling and benchmarking.

• fastThread (opens new window) - Analyze and visualize thread dumps with a free cloud-based upload interface.
• GCeasy (opens new window) - Tool to analyze and visualize GC logs. It provides a free cloud-based upload interface.
• honest-profiler (opens new window) - A low-overhead, bias-free sampling profiler.
• jHiccup (opens new window) - Logs and records platform JVM stalls.
• JITWatch (opens new window) - Analyze the JIT compiler optimisations made by the HotSpot JVM.
• JMH (opens new window) - a Java harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM.
• JProfiler (opens new window) - Database profiling for JDBC, JPA and NoSQL, with JEE support.
• LatencyUtils (opens new window) - Utilities for latency measurement and reporting.
• XRebel (opens new window) - Real-time profiling for web applications, with an in-browser widget.
• YourKit Java Profiler (opens new window) - Profiler for any application running on the JVM.

Platform

Frameworks that are suites of multiple libraries encompassing several categories.

Apache Commons

• Pool (opens new window) - Generic object pooling component.
• BCEL (opens new window) - Byte Code Engineering Library - analyze, create, and manipulate Java class files.
• Codec (opens new window) - General encoding/decoding algorithms (for example phonetic, base64, URL).
• Compress (opens new window) - Defines an API for working with tar, zip and bzip2 files.
• IO (opens new window) - Collection of I/O utilities.
• Configuration (opens new window) - Reading of configuration/preferences files in various formats.
• VFS (opens new window) - Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.
• Jelly (opens new window) - XML based scripting and processing engine.
• CSV (opens new window) - Component for reading and writing comma separated value files.
• JCS (opens new window) - Java Caching System.
• Email (opens new window) - Library for sending e-mail from Java.
• DbUtils (opens new window) - JDBC helper library.
• FileUpload (opens new window) - File upload capability for your servlets and web applications.
• Lang (opens new window) - Provides extra functionality for classes in java.lang.
• Jexl (opens new window) - Expression language which extends the Expression Language of the JSTL.
• CLI (opens new window) - Command-line arguments parser.
• Validator (opens new window) - Framework to define validators and validation rules in an xml file.
• Net (opens new window) - Collection of network utilities and protocol implementations.
• RNG (opens new window) - Commons Rng provides implementations of pseudo-random numbers generators.
• RDF (opens new window) - Common implementation of RDF 1.1 that could be implemented by systems on the JVM.
• Weaver (opens new window) - Provides an easy way to enhance (weave) compiled bytecode.
• BeanUtils (opens new window) - Easy-to-use wrappers around the Java reflection and introspection APIs.
• Collections (opens new window) - Extends or augments the Java Collections Framework.
• DBCP (opens new window) - Database connection pooling services.
• Math (opens new window) - Lightweight, self-contained mathematics and statistics components.
• Exec (opens new window) - API for dealing with external process execution and environment management in Java.
• Logging (opens new window) Wrapper around a variety of logging API implementations.
• OGNL (opens new window) - An Object-Graph Navigation Language.
• JCI (opens new window) - Java Compiler Interface.
• Daemon (opens new window) - Alternative invocation mechanism for unix-daemon-like java code.
• Functor (opens new window) - A functor is a function that can be manipulated as an object, or an object representing a single, generic function.
• Digester (opens new window) - XML-to-Java-object mapping utility.
• BSF (opens new window) - Bean Scripting Framework - interface to scripting languages, including JSR-223.
• Imaging (opens new window) - A pure-Java image library.
• SCXML (opens new window) - An implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.
• JXPath (opens new window) - Utilities for manipulating Java Beans using the XPath syntax.
• Chain (opens new window) - Chain of Responsibility pattern implementation.
• Proxy (opens new window) - Library for creating dynamic proxies.
• BeanUtils2 (opens new window) - Redesign of Commons BeanUtils.
• ClassScan (opens new window) - Find Class interfaces, methods, fields, and annotations without loading.
• CLI2 (opens new window) Redesign of Commons CLI.
• Convert (opens new window) - Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another.
• Finder (opens new window) - Java library inspired by the UNIX find command.
• Flatfile (opens new window) - Java library for working with flat data structures.
• Graph (opens new window) - A general purpose Graph APIs and algorithms.
• I18n (opens new window) - Adds the feature of localized message bundles that consist of one or many localized texts that belong together.
• Id (opens new window) - Id is a component used to generate identifiers.
• Javaflow (opens new window) - Continuation implementation to capture the state of the application.
• JNet (opens new window) - JNet allows to use dynamically register url stream handlers through the java.net API.
• Monitoring (opens new window) - Monitoring aims to provide a simple but extensible monitoring solution for Java applications.
• Nabla (opens new window) - Nabla provides automatic differentiation classes that can generate derivative of any function implemented in the Java language.
• OpenPGP (opens new window) - Interface to signing and verifying data using OpenPGP.
• Performance (opens new window) - A small framework for microbenchmark clients, with implementations for Commons DBCP and Pool.
• Pipeline (opens new window) - Provides a set of pipeline utilities designed around work queues that run in parallel to sequentially process data objects.

Other

• CUBA Platform (opens new window) - High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.
• Light-Java (opens new window) - A fast, lightweight and productive microservices framework with built-in security (opens new window).
• Orienteer (opens new window) - Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.
• Spring (opens new window) - Provides many packages for dependency injection, aspect-oriented programming, security, etc.

Processes

Libraries that help the management of operating system processes.

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

Reactive libraries

Libraries for developing reactive applications.

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

REST Frameworks

Frameworks specifically for creating RESTful services.

• Dropwizard (opens new window) - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
• Jersey (opens new window) - JAX-RS reference implementation.
• Microserver (opens new window) — A 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 (opens new window) - A simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.
• rest.li (opens new window) - 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 (opens new window) - Fully certified and portable implementation of the JAX-RS specification.
• RestExpress (opens new window) - Thin wrapper on the JBoss Netty HTTP stack that provides scaling and performance.
• Restlet Framework (opens new window) - Pioneering framework with powerful routing and filtering capabilities, and a unified client and server API.
• Spark (opens new window) - Sinatra inspired framework.
• Crnk (opens new window) - 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 (opens new window) - Standard, language-agnostic interface to REST APIs.

Science

Libraries for scientific computing, analysis and visualization.

• DataMelt (opens new window) - Environment for scientific computation, data analysis and data visualization.
• Erdos (opens new window) - Modular, light and easy graph framework for theoretic algorithms.
• GraphStream (opens new window) - Library for modeling and analyzing dynamic graphs.
• JFreeChart (opens new window) - 2D chart library for Swing, JavaFX and server-side applications.
• JGraphT (opens new window) - Graph library that provides mathematical graph-theory objects and algorithms.
• JGraphX (opens new window) - Library for visualizing (mainly Swing) and interacting with node-edge graphs.
• Mines Java Toolkit (opens new window) - Library for geophysical scientific computation, visualization and digital signal analysis.
• Morpheus (opens new window) - 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.
• Tablesaw (opens new window) - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.

Search

Engines that index documents for search and analysis.

• Apache Lucene (opens new window) - High-performance, full-featured, cross-platform, text search engine library.
• Apache Solr (opens new window) - Enterprise search engine optimized for high-volume traffic.
• Elasticsearch (opens new window) - Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.

Security

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

• Apache Shiro (opens new window) - Performs authentication, authorization, cryptography and session management.
• Bouncy Castle (opens new window) - All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.
• Cryptomator (opens new window) - Multiplatform, transparent, client-side encryption of files in the cloud.
• Hdiv (opens new window) - 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 (opens new window) - JSON web token for Java and Android.
• Jwks RSA (opens new window) - JSON Web Key Set parser.
• Keycloak (opens new window) - Integrated SSO and IDM for browser apps and RESTful web services.
• Keyczar (opens new window) - Easy-to-use, safe encryption framework with key versioning.
• Keywhiz (opens new window) - System for distributing and managing secrets.
• Nbvcxz (opens new window) - Advanced password strength estimation.
• OACC (opens new window) - Provides permission-based authorization services.
• pac4j (opens new window) - Security engine.
• PicketLink (opens new window) - Umbrella project for security and identity management.
• SecurityBuilder (opens new window) - Fluent Builder API for JCA and JSSE classes and especially X.509 certificates.
• Themis (opens new window) - 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 (opens new window) - Provides a simple and misuse-proof API for common cryptographic tasks.
• Vault (opens new window) - Secures, stores, and tightly controls access to tokens, passwords, certificates, API keys, and other secrets. It handles leasing, key revocation, key rolling, and auditing. Through a unified API, users can access an encrypted Key/Value store and network encryption-as-a-service, or generate AWS IAM/STS credentials, SQL/NoSQL databases, X.509 certificates, SSH credentials, and more.

Serialization

Libraries that handle serialization with high efficiency.

• FlatBuffers (opens new window) - Memory-efficient serialization library that can access serialized data without unpacking and parsing it.
• FST (opens new window) - JDK-compatible, high-performance object graph serialization.
• Kryo (opens new window) - Fast and efficient object graph serialization framework.
• MessagePack (opens new window) - Efficient binary serialization format.
• PHP Serializer (opens new window) - Serializing objects in the PHP serialization format.

Server

Servers specifically used to deploy applications.

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

Template Engine

Tools that substitute expressions in a template.

• Handlebars.java (opens new window) - Logicless and semantic Mustache templates.
• Jade4J (opens new window) - Implementation of Pug (formerly known as Jade).
• Jtwig (opens new window) - Modular, configurable and fully tested template engine.
• Pebble (opens new window) - 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 (opens new window) - 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 (opens new window) - DSL for synchronizing asynchronous operations.
• ConcurrentUnit (opens new window) - Toolkit for testing multi-threaded and asynchronous applications.
• GreenMail (opens new window) - In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL.
• Hoverfly Java (opens new window) - Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services.
• REST Assured (opens new window) - DSL for easy testing of REST/HTTP services.

BDD

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

• Cucumber (opens new window) - Provides a way to describe features in a plain language which customers can understand.
• Cukes-REST (opens new window) - A collection of Gherkin steps for REST-service testing using Cucumber.
• J8Spec (opens new window) - Follows a Jasmine-like syntax.
• JBehave (opens new window) - Extensively configurable framework that describes stories.
• JGiven (opens new window) - Provides a fluent API which allows for simpler composition.
• Lamdba Behave (opens new window) - Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.

Fixtures

Everything related to the creation and handling of random data.

• Beanmother (opens new window) - Sets up beans from YAML fixtures.
• Fixture Factory (opens new window) - Generates fake objects from a template.
• JFairy (opens new window) - Fake data generator.
• Randomized Testing (opens new window) - JUnit test runner and plugins for running JUnit tests with pseudo-randomness.
• Java Faker (opens new window) - A port of Ruby's fake data generator.

Frameworks

Provide environments to run tests for a specific use case.

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

Matchers

Libraries that provide custom matchers.

• AssertJ (opens new window) - Fluent assertions that improve readability.
• JSONAssert (opens new window) - Simplifies testing JSON strings.
• Truth (opens new window) - Google's assertion and proposition framework.

Miscellaneous

Other stuff related to testing.

• Mutability Detector (opens new window) - Reports whether instances of a given class are immutable.
• raml-tester (opens new window) - Tests if a request/response matches a given RAML definition.
• TestContainers (opens new window) - Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.
• pojo-tester (opens new window) - Automatically performs tests on basic POJO methods.

Mocking

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

• JMockit (opens new window) - Integration testing, API mocking and faking, and code coverage.
• Mockito (opens new window) - Mocking framework that lets you write tests with a clean and simple API.
• MockServer (opens new window) - Allows mocking of systems integrated with HTTPS.
• Moco (opens new window) - Concise web services for stubs and mocks.
• PowerMock (opens new window) - Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.
• WireMock (opens new window) - Stubs and mocks web services.

Parameterization

Simplifies the writing of parameterized tests.

• Burst (opens new window) - A unit testing library for varying test data.
• junit-dataprovider (opens new window) - A TestNG-like data provider/runner for JUnit.
• JUnitParams (opens new window) - Creates readable and maintainable parametrised tests.

Utility

Libraries which provide general utility functions.

• bucket4j (opens new window) - Rate limiting library based on token-bucket algorithm.
• cactoos (opens new window) - Collection of object-oriented primitives.
• CRaSH (opens new window) - Provides a shell into a JVM that's running CRaSH. Used by Spring Boot and others.
• Dex (opens new window) - Java/JavaFX tool capable of powerful ETL and data visualization.
• Embulk (opens new window) - Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.
• fswatch (opens new window) - Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService
• Gephi (opens new window) - Cross-platform for visualizing and manipulating large graph networks.
• Guava (opens new window) - Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.
• JADE (opens new window) - Framework and environment for building and debugging multi-agent systems.
• JavaVerbalExpressions (opens new window) - Library that helps with constructing difficult regular expressions.
• JGit (opens new window) - A lightweight, pure Java library implementing the Git version control system.
• minio-java (opens new window) - Provides simple APIs to access any Amazon S3-compatible object storage server.
• Protégé (opens new window) - Provides an ontology editor and a framework to build knowledge-based systems.
• Underscore-java (opens new window) - Port of Underscore.js functions.

Version Managers

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

• jabba (opens new window) - Java Version Manager inspired by nvm. Supports Mac OS X, Linux and Windows.
• jenv (opens new window) - Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and Mac OS X.
• SDKMan (opens new window) - 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 (opens new window) - Highly extensible, highly scalable web crawler for production environments.
• Crawler4j (opens new window) - Simple and lightweight web crawler.
• jsoup (opens new window) - Scrapes, parses, manipulates and cleans HTML.
• StormCrawler (opens new window) - SDK for building low-latency and scalable web crawlers.
• webmagic (opens new window) - Scalable crawler with downloading, url management, content extraction and persistent.

Web Frameworks

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

• Apache Tapestry (opens new window) - Component-oriented framework for creating dynamic, robust, highly scalable web applications.
• Apache Wicket (opens new window) - Component-based web application framework similar to Tapestry, with a stateful GUI.
• Blade (opens new window) - Lightweight, modular framework that aims to be elegant and simple.
• Bootique (opens new window) - Minimally opinionated framework for runnable apps.
• Firefly (opens new window) - Asynchronous framework for rapid development of high-performance web application.
• Grails (opens new window) - Groovy framework that provides a highly productive environment by favoring convention over configuration, no XML and support for mixins.
• Jooby (opens new window) - Scalable, fast and modular micro-framework that offers multiple programming models.
• Ninja (opens new window) - Full-stack web framework.
• Pippo (opens new window) - Small, highly modularized, Sinatra-like framework.
• Play (opens new window) - Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.
• PrimeFaces (opens new window) - JSF framework with both free and commercial/support versions and frontend components.
• Ratpack (opens new window) - Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications.
• Takes (opens new window) - Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.
• Vaadin (opens new window) - Event-driven framework built on top of GWT. Uses server-side architecture with Ajax on the client side.

Resources

Awesome Lists

Awesome lists related to the Java & JVM ecosystem.

• Awesome Gradle Plugins (opens new window)
• AwesomeJavaFX (opens new window)
• Awesome JVM (opens new window)
• Awesome Microservices (opens new window)
• Awesome REST (opens new window)
• Awesome Selenium (opens new window)
• ciandcd (opens new window)
• Useful Java Links (opens new window)

Communities

Active discussions.

• r/java (opens new window) - Subreddit for the Java community.
• stackoverflow (opens new window) - Question/answer platform.
• VirtualJUG (opens new window) - Virtual Java User Group.

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 (opens new window)

Influential Books

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

• Core Java Volume I--Fundamentals (opens new window)
• Core Java, Volume II--Advanced Features (opens new window)
• Effective Java (3rd Edition) (opens new window)
• Java Concurrency in Practice (opens new window)
• Thinking in Java (opens new window)

Podcasts and Screencasts

Something to look at or listen to while programming.

• Java Off Heap (opens new window)
• Marco Behler's Screencasts (opens new window) - Screencasts about modern Java development.
• The Java Council (opens new window)
• The Java Posse (opens new window) - Discontinued as of 02/2015.

Twitter

Active accounts to follow. Descriptions from Twitter.

• Adam Bien (opens new window) - Freelance author, JavaOne Rockstar speaker, consultant, Java Champion.
• Aleksey Shipilëv (opens new window) - Performance geek, benchmarking czar, concurrency bug hunter.
• Antonio Goncalves (opens new window) - Java Champion, JUG Leader, Devoxx France, Java EE 6/7, JCP, Author.
• Arun Gupta (opens new window) - Java Champion, JavaOne Rockstar, JUG Leader, Devoxx4Kids-er, VP of Developer Advocacy at Couchbase.
• Brian Goetz (opens new window) - Java Language Architect at Oracle.
• Bruno Borges (opens new window) - Product Manager/Java Jock at Oracle.
• Chris Richardson (opens new window) - Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, *POJOs in Action- author.
• Ed Burns (opens new window) - Consulting Member of the Technical Staff at Oracle.
• Eugen Paraschiv (opens new window) - Author of the Spring Security Course.
• Heinz Kabutz (opens new window) - Java Champion, speaker, author of The Java Specialists' Newsletter, concurrency performance expert.
• Holly Cummins (opens new window) - Technical Lead of IBM London's Bluemix Garage, Java Champion, developer, author, JavaOne rockstar.
• James Weaver (opens new window) - Java/JavaFX/IoT developer, author and speaker.
• Java EE (opens new window) - Official Java EE Twitter account.
• Java Magazine (opens new window) - Official Java Magazine account.
• Java (opens new window) - Official Java Twitter account.
• Javin Paul (opens new window) - Well-known Java blogger.
• Josh Long (opens new window) - Spring Advocate at Pivotal, author of O'Reilly's Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star.
• Lukas Eder (opens new window) - Java Champion, speaker, JUG.ch co-leader, Founder and CEO Data Geekery (jOOQ).
• Mario Fusco (opens new window) - RedHatter, JUG coordinator, frequent speaker and author.
• Mark Heckler (opens new window) - Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud.
• Mark Reinhold (opens new window) - Chief Architect, Java Platform Group, Oracle.
• Markus Eisele (opens new window) - Java EE evangelist, Red Hat.
• Martijn Verburg (opens new window) - London JUG co-leader, speaker, author, Java Champion and much more.
• Martin Thompson (opens new window) - Pasty faced performance gangster.
• Monica Beckwith (opens new window) - Performance consultant, JavaOne Rock Star.
• OpenJDK (opens new window) - Official OpenJDK account.
• Peter Lawrey (opens new window) - Peter Lawrey, Java performance expert.
• Randy Shoup (opens new window) - Stitch Fix VP Engineering, speaker, JavaOne Rock Star.
• Reza Rahman (opens new window) - Java EE/GlassFish/WebLogic evangelist, author, speaker, open source hacker.
• Simon Maple (opens new window) - Java Champion, VirtualJUG founder, LJC leader, RebelLabs author.
• Stephen Colebourne (opens new window) - Java Champion, speaker.
• Trisha Gee (opens new window) - Java Champion and speaker.
• Venkat Subramaniam (opens new window) - Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion.

Websites

Sites to read.

• Google Java Style (opens new window)
• InfoQ (opens new window)
• Java Algorithms and Clients (opens new window)
• Java, SQL, and jOOQ (opens new window)
• Java.net (opens new window)
• Javalobby (opens new window)
• JavaWorld (opens new window)
• JAXenter (opens new window)
• RebelLabs (opens new window)
• The Takipi Blog (opens new window)
• TheServerSide.com (opens new window)
• Vanilla Java (opens new window)
• Voxxed (opens new window)

Contributing

Contributions are very welcome!

Please have a look at the CONTRIBUTING (opens new window) guidelines.