- Awesome Java
- Bean Mapping
- Bytecode Manipulation
- Cluster Management
- Code Analysis
- Code Coverage
- Code Generators
- Command-line Argument Parsers
- Constraint Satisfaction Problem Solver
- Data structures
- Date and Time
- Dependency Injection
- Distributed Applications
- Distributed Transactions
- Document Processing
- Formal Verification
- Functional Programming
- Game Development
- High Performance
- HTTP Clients
- Hypermedia Types
- JSON Processing
- JVM and JDK
- Machine Learning
- Natural Language Processing
- Performance analysis
- Reactive libraries
- REST Frameworks
- Template Engine
- Version Managers
- Web Crawling
- Web Frameworks
Frameworks that ease bean mapping.
- Dozer - Mapper that copies data from one object to another using annotations and API or XML configuration.
- 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.
- Selma - Annotation processor-based bean mapper.
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.
- Gradle - Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven’s dependency management.
Libraries to manipulate bytecode programmatically.
- ASM - All-purpose, low-level bytecode manipulation and analysis.
- Byte Buddy - Further simplifies bytecode generation with a fluent API.
- Byteman - Manipulate bytecode at runtime via DSL (rules); mainly for testing/troubleshooting.
- cglib - Bytecode generation library.
- Javassist - Tries to simplify bytecode editing.
Libraries that provide caching facilities.
- Caffeine - High-performance, near-optimal caching library.
- Ehcache - Distributed general-purpose cache.
- Infinispan - Highly concurrent key/value datastore used for caching.
Frameworks that can dynamically manage applications inside of a cluster.
- Apache Aurora - Mesos framework for long-running services and cron jobs.
- Apache Mesos - Abstracts CPU, memory, storage, and other compute resources away from machines.
- Singularity - Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.
Tools that provide metrics and quality measurements.
- Checkstyle - Static analysis of coding conventions and standards.
- Error Prone - Catches common programming mistakes as compile-time errors.
- Infer - Modern static analysis tool for verifying the correctness of code.
- jQAssistant - Static code analysis with Neo4J-based query language.
- NullAway - Eliminates NullPointerExceptions with low build-time overhead.
- PMD - Source code analysis for finding bad coding practices.
- SonarJava - Static analyzer for SonarQube & SonarLint.
- Sourcetrail - Visual source code navigator.
- Spoon - Library for analyzing and transforming Java source code.
- Spotbugs - Static analysis of bytecode to find potential bugs.
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.
- JaCoCo - Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.
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.
- FreeBuilder - Automatically generates the Builder pattern.
- 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.
- Lombok - Code generator that aims to reduce verbosity.
Libraries that make it easy to parse command line options, arguments, etc.
- Airline - Annotation-based framework for parsing Git-like command-line arguments.
- args4j - Small library to parse command-line arguments.
- JCommander - Command-line argument-parsing framework with custom types and validation via implementing interfaces.
- JOpt Simple - Simple parser that uses the POSIX getopt() and GNU getopt_long() syntaxes. Uses a fluent API instead of annotations.
- picocli - ANSI colors and styles in usage help. Can be included as source to avoid dependency. Annotation-based, POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.
Frameworks that help to create parsers, interpreters or compilers.
Libraries that provide external configuration.
- centraldogma - Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.
- cfg4j - Modern configuration library for distributed apps written in Java.
- config - Configuration library for JVM languages.
- dotenv - A twelve-factor configuration library for Java.
- ini4j - Provides an API for handling Windows’ INI files.
- KAConf - Annotation-based configuration system for Java and Kotlin.
- owner - Reduces boilerplate of properties.
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.
- OptaPlanner - Business planning and resource scheduling optimization solver.
Frameworks and libraries that simplify reading/writing CSV data.
- 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.
Everything that simplifies interactions with the database.
- Apache Phoenix - High-performance relational database layer over HBase for low-latency applications.
- Chronicle Map - Efficient, in-memory (opt. persisted to disk), off-heap key-value store.
- eXist - A NoSQL document database and application platform.
- 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.
- 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.
- 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.
- OrientDB - Embeddable distributed database written on top of Hazelcast.
- Presto - Distributed SQL query engine for big data.
- Querydsl - Typesafe unified queries.
- 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 - 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 - Database access library that utilizes Java 8’s Stream API for querying.
- sql2o - Thin JDBC wrapper that simplifies database access and provides simple mapping of ResultSets to POJOs.
- Vibur DBCP - JDBC connection pool library with advanced performance monitoring capabilities.
- Xodus - Highly concurrent transactional schema-less and ACID-compliant embedded database.
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 - A big, fast and persistent queue based on memory-mapped files.
- Persistent Collection - Persistent and immutable analogue of the Java Collections Framework.
- Protobuf - Google’s data interchange format.
- SBE - Simple Binary Encoding, one of the fastest message formats around.
- Tape - A lightning-fast, transactional, file-based FIFO.
- Wire - Clean, lightweight protocol buffers.
Libraries related to handling date and time.
- Almanac Converter - Simple conversion between different calendar systems.
- iCal4j - Parse and build iCalendar RFC 5545 data models.
- ThreeTen-Extra - Additional date-time classes that complement those in JDK 8.
- Time4J - Advanced date and time library.
Libraries that help to realize the Inversion of Control paradigm.
- Apache DeltaSpike - CDI extension framework.
- Dagger2 - 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.
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.
- 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.
- JavaParser - Parse, modify and generate Java code.
- JavaSymbolSolver - A symbol solver for Java.
- JRebel - Instantly reloads code and configuration changes without redeploys.
- NoException - Allows checked exceptions in functional interfaces and converts exceptions to Optional return.
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 - Framework for creating CQRS applications.
- Copycat - Fault-tolerant state machine replication framework.
- Dropwizard Circuit Breaker - Circuit breaker design pattern for Dropwizard.
- Failsafe - Simple failure handling with retries and circuit breakers.
- Hazelcast - Highly scalable in-memory datagrid with a free open-source version.
- Hystrix - Provides latency and fault tolerance.
- JGroups - Toolkit for reliable messaging and cluster creation.
- Orbit - Virtual actors; adds another level of abstraction to traditional actors.
- Quasar - Lightweight threads and actors for the JVM.
- resilience4j - Functional fault tolerance library.
- ScaleCube - Embeddable Cluster-Membership library based on SWIM and gossip protocol.
- Zuul - A gateway service that provides dynamic routing, monitoring, resiliency, security, and more.
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 - A 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.
Tools that handle the distribution of applications in native formats.
- Bintray - 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 - 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.
- IzPack - Setup authoring tool for cross-platform deployments.
- JitPack - Easy-to-use package repository for GitHub. Builds Maven/Gradle projects on demand and publishes ready-to-use packages.
- Nexus - Binary management with proxy and caching capabilities.
- packr - Packs JARs, assets and the JVM for native distribution on Windows, Linux and Mac OS X.
- really-executable-jars-maven-plugin - Maven plugin for making self-executing JARs.
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.
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.
- 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.
- 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.
- OpenJML - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers.
Libraries that facilitate functional programming.
- cyclops-react - 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.
- 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.
Frameworks that support the development of games.
- FXGL - JavaFX Game Development Framework.
- jMonkeyEngine - Game engine for modern 3D development.
- libGDX - All-round cross-platform, high-level framework.
- LWJGL - Robust framework that abstracts libraries like OpenGL/CL/AL.
Libraries for working with geospatial data and algorithms.
- Apache SIS - Library for developing geospatial applications.
- Geo - GeoHash utilities in Java.
- Geotoolkit.org - Library for developing geospatial applications. Built on top of the Apache SIS project.
- GeoTools - Library that provides tools for geospatial data.
- GraphHopper - Road-routing engine. Used as a Java library or standalone web service.
- H2GIS - A spatial extension of the H2 database.
- Jgeohash - Library for using the GeoHash algorithm.
- Mapsforge - Map rendering based on OpenStreetMap data.
- Spatial4j - General-purpose spatial/geospatial library.
Libraries to create modern graphical user interfaces.
- JavaFX - The successor of Swing.
- Scene Builder - Visual layout tool for JavaFX applications.
- SWT - The Standard Widget Toolkit, a graphical widget toolkit.
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 - Hash sets and hash maps.
Libraries that assist with creating HTTP requests and/or binding responses.
- Async Http Client - Asynchronous HTTP and WebSocket client library.
- Feign - HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.
- OkHttp - HTTP+SPDY client.
- restQL-core - Microservice query language that fetches information from multiple services.
- Retrofit - Typesafe REST client.
- Ribbon - Client-side IPC library that is battle-tested in cloud.
- Riptide - Client-side response routing for Spring’s RestTemplate.
Libraries that handle serialization to hypermedia types.
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.
- NetBeans - Provides integration for several Java SE and EE features, from database access to HTML5.
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 - A 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.
Libraries for serializing and deserializing JSON to and from Java objects.
- 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.
Libraries for processing data in JSON format.
- 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.
Current implementations of the JVM/JDK.
- Avian - JVM with both JIT and AOT modes. Includes an iOS port.
- OpenJ9 - 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 - Open-source implementation for Linux.
- ParparVM - VM with non-blocking, concurrent GC for iOS.
- Zulu OpenJDK 9 - Early-access OpenJDK 9 builds for Windows, Linux, and Mac OS X.
- Zulu OpenJDK - OpenJDK builds for Windows, Linux, and Mac OS X through Java 8.
Libraries that log the behavior of an application.
- Apache Log4j 2 - Complete rewrite with a powerful plugin and configuration architecture.
- Graylog - Open-source aggregator suited for extended role and permission management.
- 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.
- SLF4J - Abstraction layer/simple logging facade.
- tinylog - Lightweight logging framework with static logger class.
- Tracer - Call tracing and log correlation in distributed systems.
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.
- Apache Spark - Data analytics cluster-computing framework.
- DatumBox - Provides several algorithms and pre-trained models for natural language processing.
- DeepDive - Creates structured information from unstructured data and integrates it into an existing database.
- Deeplearning4j - Distributed and multi-threaded deep learning library.
- H2O - Analytics engine for statistics over big data.
- JSAT - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution.
- Oryx 2 - Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
- Smile - The Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.
- Weka - Collection of algorithms for data mining tasks ranging from pre-processing to visualization.
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.
- Hermes - Fast and reliable message broker built on top of Kafka.
- JeroMQ - Implementation of ZeroMQ.
- Nakadi - Provides a RESTful API on top of Kafka.
- RocketMQ - A fast, reliable, and scalable distributed messaging platform.
- Smack - Cross-platform XMPP client library.
- Codename One - Cross-platform solution for writing native mobile apps.
- CQEngine - Ultra-fast, SQL-like queries on Java collections.
- Design Patterns - Implementation and explanation of the most common design patterns.
- Failsafe - Simple failure handling with retries and circuit breakers.
- FF4J - Feature Flags for Java.
- J2ObjC - Java-to-Objective-C translator for porting Android libraries to iOS.
- JavaX - Reinventing and extending Java with a focus on simplicity.
- JBake - Static website generator.
- JBot - Framework for building chatbots.
- Jimfs - In-memory file system.
- Joda-Money - Basic currency and money classes and algorithms not provided by the JDK.
- JPad - Snippet runner.
- Lanterna - Easy console text-GUI library, similar to curses.
- LightAdmin - Pluggable CRUD UI library for rapid application development.
- Maven Wrapper - Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.
- Membrane Service Proxy - An open-source, reverse-proxy framework written in Java.
- MinimalFTP - Lightweight, small and customizable FTP server.
- Modern Java - A Guide to Java 8 - Popular Java 8 guide.
- Modernizer - Detect uses of legacy Java APIs.
- Multi-OS Engine - An open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.
- OpenRefine - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
- Polyglot for Maven - Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.
- Smooks - Extensible framework for building applications that process data which means bindings, transformations, message processing and enrichment.
- Togglz - Implementation of the Feature Toggles pattern.
- TypeTools - Tools for resolving generic types.
- XMLBeam - Processes XML by using annotations or XPath within code.
- OctoLinker - Browser extension which allows to navigate through code on GitHub more efficiently.
Tools for managing microservices: i.e., creation, coordination or discovery.
- Apollo - Libraries for writing composable microservices.
- 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.
- Lagom - Framework for creating microservice-based systems.
Tools that monitor applications in production.
- AppDynamics - Performance monitor.
- Automon - Combines the power of AOP with monitoring and/or logging tools.
- BugSnag - Exception and error monitoring with an integration of several third party tools for a better workflow and a free hobbyist tier.
- Failsafe Actuator - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
- Glowroot - Open-source Java APM.
- inspectIT - Captures detailed run-time information via hooks that can be changed on the fly. It supports tracing over multiple systems via the OpenTracing API and can correlate the data with end user monitoring.
- Instrumental - Real-time Java application performance monitoring. A commercial service with free development accounts.
- 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.
- Kamon - Tool for monitoring applications running on the JVM.
- Metrics - Expose metrics via JMX or HTTP and send them to a database.
- New Relic - Performance monitor.
- nudge4j - Remote developer console from the browser for Java 8 via bytecode injection.
- OverOps - In-production error monitoring and debugging.
- Pinpoint - Open-source APM tool.
- Prometheus - Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.
- 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.
For working with platform-specific native libraries.
- 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.
Libraries that specialize in processing text.
- CogCompNLP - Provides common annotators for plain text input.
- CoreNLP - Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis.
- DKPro - Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.
- LingPipe - Toolkit for tasks ranging from POS tagging to sentiment analysis.
Libraries for building network servers.
- Comsat - Integrates standard Java web-related APIs with Quasar fibers and actors.
- Dubbo - High-performance RPC framework.
- Finagle - 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 - 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.
- Nifty - Implementation of Thrift clients and servers on Netty.
- sshj - Programatically use SSH, SCP or SFTP.
- Undertow - Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly.
- urnlib - Represent, parse and encode URNs, as in RFC 2141.
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.
- 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.
- MyBatis - Couples objects with stored procedures or SQL statements.
- SimpleFlatMapper - Simple database and CSV mapper.
Java platform as a service.
- AWS Elastic Beanstalk - AWS-based, with support for Tomcat and Jetty.
- AWS Lambda - Serverless computation.
- Google App Engine - PaaS on Google’s infrastructure.
- Heroku - Abstract computing environments.
- Jelastic - Supports Tomcat, Jetty, GlassFish, JBoss, TomEE and WildFly.
- OpenShift Enterprise - On-premise solution.
Tools to help with PDF file creation.
- Apache FOP - Creates PDFs from XSL-FO.
- Apache PDFBox - Toolbox for creating and manipulating PDFs.
- Dynamic Jasper - Abstraction layer to JasperReports.
- DynamicReports - Simplifies JasperReports.
- flyingsaucer - XML/XHTML and CSS 2.1 renderer.
- iText - Creates PDF files programmatically.
- JasperReports - Complex reporting engine.
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 - A 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 - a Java harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM.
- JProfiler - Database profiling for JDBC, JPA and NoSQL, with JEE support.
- LatencyUtils - Utilities for latency measurement and reporting.
- XRebel - Real-time profiling for web applications, with an in-browser widget.
- YourKit Java Profiler - Profiler for any application running on the JVM.
Frameworks that are suites of multiple libraries encompassing several categories.
- CUBA Platform - High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.
- Light-Java - A 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.
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.
- vert.x - Polyglot event-driven application framework.
Frameworks specifically for creating RESTful services.
- Dropwizard - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
- Jersey - JAX-RS reference implementation.
- Microserver — 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 - A 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.
Libraries for scientific computing, analysis and visualization.
- DataMelt - Environment for scientific computation, data analysis and data visualization.
- Erdos - Modular, light and easy graph framework for theoretic algorithms.
- GraphStream - Library for modeling and analyzing dynamic graphs.
- JGraphT - Graph library that provides mathematical graph-theory objects and algorithms.
- JGraphX - Library for visualizing (mainly Swing) and interacting with node-edge graphs.
- 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.
- Tablesaw - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.
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.
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.
- Cryptomator - Multiplatform, transparent, client-side encryption of files in the cloud.
- 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.
- Keycloak - Integrated SSO and IDM for browser apps and RESTful web services.
- Keyczar - Easy-to-use, safe encryption framework with key versioning.
- Keywhiz - System for distributing and managing secrets.
- Nbvcxz - Advanced password strength estimation.
- OACC - Provides permission-based authorization services.
- pac4j - Security engine.
- PicketLink - Umbrella project for security and identity management.
- Vault - 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.
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.
- Kryo - Fast and efficient object graph serialization framework.
- MessagePack - Efficient binary serialization format.
- PHP Serializer - Serializing objects in the PHP serialization format.
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.
- WebSphere Liberty - Lightweight, modular server developed by IBM.
- WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support.
Tools that substitute expressions in a template.
- Handlebars.java - Logicless and semantic Mustache templates.
- Jade4J - Implementation of Pug (formerly known as Jade).
- 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.
- Thymeleaf - Aims to be a substitute for JSP and works for XML files.
Tools that test from model to the view.
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.
- Hoverfly Java - Native bindings for Hoverfly, a proxy which allows you to simulate HTTP services.
- REST Assured - DSL for easy testing of REST/HTTP services.
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 - A 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.
Everything related to the creation and handling of random data.
- Beanmother - Sets up beans from YAML fixtures.
- Fixture Factory - Generates fake objects from a template.
- JFairy - Fake data generator.
- Randomized Testing - JUnit test runner and plugins for running JUnit tests with pseudo-randomness.
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.
- Pact JVM - Consumer-driven contract testing.
- PIT - Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.
Libraries that provide custom matchers.
- AssertJ - Fluent assertions that improve readability.
- JSONAssert - Simplifies testing JSON strings.
- Truth - Google’s assertion and proposition framework.
Other stuff related to testing.
- Mutability Detector - Reports whether instances of a given class are immutable.
- raml-tester - Tests if a request/response matches a given RAML definition.
- TestContainers - Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.
- pojo-tester - Automatically performs tests on basic POJO methods.
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.
Simplifies the writing of parameterized tests.
- Burst - A unit testing library for varying test data.
- junit-dataprovider - A TestNG-like data provider/runner for JUnit.
- JUnitParams - Creates readable and maintainable parametrised tests.
Libraries which provide general utility functions.
- Apache Commons - Provides configuration, validation, collections, file uploading, XML processing and other general-purpose functions.
- cactoos - Collection of object-oriented primitives.
- CRaSH - Provides a shell into a JVM that’s running CRaSH. Used by Spring Boot and others.
- Dex - Java/JavaFX tool capable of powerful ETL and data visualization.
- Embulk - Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.
- Gephi - Cross-platform for visualizing and manipulating large graph networks.
- 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.
- JavaVerbalExpressions - Library that helps with constructing difficult regular expressions.
- JGit - A lightweight, pure Java library implementing the Git version control system.
- 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.
- Underscore-java - Port of Underscore.js functions.
Utilities that help create the development shell environment and switch between different Java versions.
- jabba - Java Version Manager inspired by nvm. Supports Mac OS X, Linux and Windows.
- jenv - Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and Mac OS X.
- SDKMan - Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms and Windows.
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.
Frameworks that handle the communication between the layers of a web application.
- 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.
- Grails - Groovy framework that provides a highly productive environment by favoring convention over configuration, no XML and support for mixins.
- 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 built on top of GWT. Uses server-side architecture with Ajax on the client side.
Awesome lists related to the Java & JVM ecosystem.
- Awesome Gradle Plugins
- Awesome JVM
- Awesome Microservices
- Awesome REST
- Awesome Selenium
- Useful Java Links
- r/java - Subreddit for the Java community.
- stackoverflow - Question/answer platform.
- VirtualJUG - Virtual Java User Group.
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.
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)
- Java Concurrency in Practice
- Thinking in Java
Something to look at or listen to while programming.
- Java Off Heap
- Marco Behler’s Screencasts - Screencasts about modern Java development.
- The Java Council
- The Java Posse - Discontinued as of 02/2015.
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 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, JUG.ch co-leader, Founder and CEO Data Geekery (jOOQ).
- 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.
- Simon Maple - Java Champion, VirtualJUG founder, LJC leader, RebelLabs author.
- 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.
Sites to read.