- [dOOv](https://github.com/doov-io/doov) - Provides fluent API for typesafe domain model validation and mapping. It uses annotations, code generation and a type safe DSL to make bean validation and mapping fast and easy.
- [JMapper](https://github.com/jmapper-framework/jmapper-core) - Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.
- [MapStruct](https://github.com/mapstruct/mapstruct) - Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.
- [Orika](https://github.com/orika-mapper/orika) - JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.
- [reMap](https://github.com/remondis-it/remap) - Lambda and method handle-based mapping which requires code and not annotations if objects have different names.
- [Apache Maven](https://maven.apache.org) - 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.
- [Perses](https://github.com/nicolasmanic/perses) - Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.
- [JOpt Simple](https://jopt-simple.github.io/jopt-simple/) - Fluent parser that uses the POSIX#getopt and GNU#getopt_long syntaxes.
- [picocli](https://picocli.info) - ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.
- [Apache Aurora](https://aurora.apache.org) - Mesos framework for long-running services and cron jobs.
- [Singularity](http://getsingularity.com) - Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.
- [Clover](https://www.atlassian.com/software/clover) - Relies on source-code instrumentation instead of bytecode instrumentation.
- [Cobertura](https://cobertura.github.io/cobertura/) - Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)
- [JaCoCo](https://www.eclemma.org/jacoco/) - Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.
- [centraldogma](https://github.com/line/centraldogma) - Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.
- [cfg4j](https://github.com/cfg4j/cfg4j) - Modern configuration library for distributed apps written in Java.
- [Configurate](https://github.com/SpongePowered/Configurate) - Configuration library with support for various configuration formats and transformations.
- [microconfig](https://microconfig.io) - Configuration system designed for microservices which helps to separate configuration from code. The configuration for different services can have common and specific parts and can be dynamically distributed.
- [uniVocity-parsers](https://github.com/uniVocity/univocity-parsers) - One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.
- [Apache Avro](https://avro.apache.org) - Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.
- [Apache Orc](https://orc.apache.org) - Fast and efficient columnar storage format for Hadoop-based workloads.
- [Apache Parquet](https://parquet.apache.org) - Columnar storage format based on assembly algorithms from Google's paper on Dremel.
- [Apache Thrift](https://thrift.apache.org) - Data interchange format that originated at Facebook.
- [Big Queue](https://github.com/bulldog2011/bigqueue) - Fast and persistent queue based on memory-mapped files.
- [HyperMinHash-java](https://github.com/LiveRamp/HyperMinHash-java) - Probabilistic data structure for computing union, intersection, and set cardinality in loglog space.
- [Persistent Collection](https://github.com/hrldcpr/pcollections) - Persistent and immutable analogue of the Java Collections Framework.
- [Protobuf](https://github.com/protocolbuffers/protobuf) - Google's data interchange format.
- [Apache Calcite](https://calcite.apache.org) - Dynamic data management framework. It contains many of the pieces that comprise a typical database management system.
- [Spring Data JPA MongoDB Expressions](https://github.com/mhewedy/spring-data-jpa-mongodb-expressions) - Allows you to use MongoDB query language to query your relational database.
- [Redisson](https://github.com/redisson/redisson) - Allows for distributed and scalable data structures on top of a Redis server.
- [requery](https://github.com/requery/requery) - Modern, lightweight but powerful object mapping and SQL generator. Easily map to or create databases, or perform queries and updates from any Java-using platform.
- [Faux Pas](https://github.com/zalando/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.
- [JavaSymbolSolver](https://github.com/javaparser/javasymbolsolver) - Symbol solver.
- [Manifold](https://github.com/manifold-systems/manifold) - Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.
- [SneakyThrow](https://github.com/rainerhahnekamp/sneakythrow) - Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations.
- [Apache Geode](https://geode.apache.org) - In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.
- [Apache ZooKeeper](https://zookeeper.apache.org) - Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.
- [Bitronix](https://github.com/bitronix/btm) - Simple but complete implementation of the JTA 1.1 API.
- [Narayana](https://narayana.io) - Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards. (LGPL-2.1-only)
- [Seata](https://github.com/seata/seata) - Delivers high performance and easy to use distributed transaction services under a microservices architecture.
- [Capsule](https://github.com/puniverse/capsule) - Simple and powerful packaging and deployment. A fat JAR on steroids, or a "Docker for Java" that supports JVM-optimized containers.
- [Central Repository](https://search.maven.org) - 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.
- [Getdown](https://github.com/threerings/getdown) - A system for deploying Java applications to end-user computers and keeping them up to date. Developed as an alternative to Java Web Start.
- [JavaPackager](https://github.com/fvarrui/JavaPackager) - Maven and Gradle plugin which provides an easy way to package Java applications in native Windows, Mac OS X or GNU/Linux executables, and generate installers for them.
- [zerocell](https://github.com/creditdatamw/zerocell) - Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead.
- [Checker Framework](https://checkerframework.org) - Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)
- [Java Path Finder (JPF)](https://github.com/javapathfinder/jpf-core) - JVM formal verification tool containing a model checker and more. Created by NASA.
- [JMLOK 2.0](https://massoni.computacao.ufcg.edu.br/home/jmlok) - Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected. (GPL-3.0-only)
- [KeY](https://www.key-project.org) - Formal software development tool that aims to integrate design, implementation, formal specification, and formal verification of object-oriented software as seamlessly as possible. Uses JML for specification and symbolic execution for verification. (GPL-2.0-or-later)
- [OpenJML](http://www.openjml.org) - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)
- [Cyclops](https://github.com/aol/cyclops) - Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.
- [derive4j](https://github.com/derive4j/derive4j) - Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms. (GPL-3.0-only)
- [Fugue](https://bitbucket.org/atlassian/fugue) - Functional extensions to Guava.
- [Functional Java](http://www.functionaljava.org) - Implements numerous basic and advanced programming abstractions that assist composition-oriented development.
- [jOOλ](https://github.com/jOOQ/jOOL) - 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](https://github.com/poetix/protonpack) - Collection of stream utilities.
- [Koloboke](https://github.com/leventov/Koloboke) - Carefully designed extension of the Java Collections Framework with primitive specializations and more.
- [Google HTTP Client](https://github.com/googleapis/google-http-java-client) - Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf.
- [IntelliJ IDEA ![c]](https://www.jetbrains.com/idea/) - Supports many JVM languages and provides good options for Android development. The commercial edition targets the enterprise sector.
- [jGRASP](https://www.jgrasp.org) - Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer.
- [Visual Studio Code](https://code.visualstudio.com/docs/languages/java) - Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace.
- [image-comparison](https://github.com/romankh3/image-comparison) - Library that compares 2 images with the same sizes and shows the differences visually by drawing rectangles. Some parts of the image can be excluded from the comparison. Can be used for automation qa tests.
- [ClassGraph](https://github.com/classgraph/classgraph) - ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.
- [Mirror](http://projetos.vidageek.net/mirror/mirror/) - Mirror was created to bring light to a simple problem, usually named ReflectionUtil, which is on almost all projects that rely on reflection to do advanced tasks.
- [Objenesis](http://objenesis.org) - Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions.
- [ReflectASM](https://github.com/EsotericSoftware/reflectasm) - ReflectASM is a very small Java library that provides high performance reflection by using code generation.
- [Reflections](https://github.com/ronmamo/reflections) - Reflections scans your classpath, indexes the metadata, allows you to query it on runtime and may save and collect that information for many modules within your project.
- [JobRunr](https://github.com/jobrunr/jobrunr) - Job scheduling library which utilizes lambdas for fire-and-forget, delayed and recurring jobs. Guarantees execution by single scheduler instance using optimistic locking. Has features for persistence, minimal dependencies and is embeddable.
- [Quartz](https://github.com/quartz-scheduler/quartz) - Feature-rich, open source job scheduling library that can be integrated within virtually any Java application.
- [Sundial](https://github.com/knowm/Sundial) - Lightweight framework to simply define jobs, define triggers and start the scheduler.
- [Wisp](https://github.com/Coreoz/Wisp) - Simple library with minimal footprint and straightforward API.
- [db-scheduler](https://github.com/kagkarlsson/db-scheduler) - Persistent and cluster-friendly scheduler.
- [easy-batch](https://github.com/j-easy/easy-batch) - Set up batch jobs with simple processing pipelines. Records are read in sequence from a data source, processed in pipeline and written in batches to a data sink.
- [shedlock](https://github.com/lukas-krecan/ShedLock) - Makes sure that your scheduled tasks are executed at most once at the same time. If a task is being executed on one node, it acquires a lock which prevents execution of the same task from another node or thread.
- [Gson](https://github.com/google/gson) - Serializes objects to JSON and vice versa. Good performance with on-the-fly usage.
- [HikariJSON](https://github.com/brettwooldridge/HikariJSON) - High-performance JSON parser, 2x faster than Jackson.
- [jackson-modules-java8](https://github.com/FasterXML/jackson-modules-java8) - Set of Jackson modules for Java 8 datatypes and features.
- [Jackson-datatype-money](https://github.com/zalando/jackson-datatype-money) - Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types.
- [Jackson](https://github.com/FasterXML/jackson) - Similar to GSON, but offers performance gains if you need to instantiate the library more often.
- [JSON-io](https://github.com/jdereg/json-io) - Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer.
- [jsoniter](http://jsoniter.com) - Fast and flexible library with iterator and lazy parsing API.
- [LoganSquare](https://github.com/bluelinelabs/LoganSquare) - JSON parsing and serializing library based on Jackson's streaming API. Outperforms GSON & Jackson's library.
- [Moshi](https://github.com/square/moshi) - Modern JSON library, less opinionated and uses built-in types like List and Map.
- [Corretto](https://aws.amazon.com/corretto/) - No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)
- [Dragonwell8](https://github.com/alibaba/dragonwell8) - Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.
- [OpenJ9](https://github.com/eclipse/openj9) - High performance, enterprise-calibre, flexibly licensed, openly-governed cross-platform JVM extending and augmenting the runtime technology components from the Eclipse OMR and OpenJDK project.
- [ParparVM](https://github.com/codenameone/CodenameOne/tree/master/vm) - VM with non-blocking, concurrent GC for iOS. (GPL-2.0-only WITH Classpath-exception-2.0)
- [RedHat Open JDK](https://developers.redhat.com/products/openjdk/overview) - RedHat's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)
- [tinylog](https://tinylog.org/v2/) - Lightweight logging framework with static logger class.
- [OpenTracing Toolbox](https://github.com/zalando/opentracing-toolbox) - Collection of libraries that build on top of OpenTracing and provide extensions and plugins to existing instrumentations.
- [JSAT](https://github.com/EdwardRaff/JSAT) - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)
- [oj! Algorithms](https://www.ojalgo.org/) - High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing.
- [Oryx 2](https://github.com/OryxProject/oryx) - Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.
- [Smile](https://github.com/haifengl/smile) - Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.
- [Tribuo](https://tribuo.org/) - Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.
- [Weka](https://www.cs.waikato.ac.nz/ml/weka/) - Collection of algorithms for data mining tasks ranging from pre-processing to visualization. (GPL-3.0-only)
- [Armeria](https://github.com/line/armeria) - Asynchronous RPC/REST client/server library built on top of Java 8, Netty, HTTP/2, Thrift and gRPC.
- [consul-api](https://github.com/Ecwid/consul-api) - Client for the Consul API: a distributed, highly available and datacenter-aware registry/discovery service.
- [Eureka](https://github.com/Netflix/eureka) - REST-based service registry for resilient load balancing and failover.
- [Helidon](https://helidon.io) - Two-style approach for writing microservices: Functional-reactive and as an implementation of MicroProfile.
- [FizzBuzz Enterprise Edition](https://github.com/EnterpriseQualityCoding/FizzBuzzEnterpriseEdition) - No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)
- [OpenRefine](http://openrefine.org) - Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.
- [Polyglot for Maven](https://github.com/takari/polyglot-maven) - Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.
- [Failsafe Actuator](https://github.com/zalando/failsafe-actuator) - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
- [inspectIT](https://www.inspectit.rocks) - 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 ![c]](https://instrumentalapp.com) - Real-time Java application performance monitoring. A commercial service with free development accounts.
- [JavaMelody](https://github.com/javamelody/javamelody) - Performance monitoring and profiling.
- [jmxtrans](https://github.com/jmxtrans/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.
- [Stagemonitor](https://github.com/stagemonitor/stagemonitor) - Open-source performance monitoring and transaction tracing for JVM apps.
- [Sysmon](https://github.com/palantir/Sysmon) - Lightweight platform monitoring tool for Java VMs.
- [zipkin](https://zipkin.io) - Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures.
- [JavaCPP](https://github.com/bytedeco/javacpp) - Provides efficient and easy access to native C++.
- [JNA](https://github.com/java-native-access/jna) - Work with native libraries without writing JNI. Also provides interfaces to common system libraries.
- [JNR](https://github.com/jnr/jnr-ffi) - Work with native libraries without writing JNI. Also provides interfaces to common system libraries. Same goals as JNA, but faster, and serves as the basis for the upcoming [Project Panama](http://openjdk.java.net/projects/panama).
- [CogCompNLP](https://github.com/CogComp/cogcomp-nlp) - Provides common annotators for plain text input. (Research and Academic Use License)
- [CoreNLP](https://nlp.stanford.edu/software/corenlp.shtml) - Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis. (GPL-3.0-or-later)
- [gRPC](https://github.com/grpc/grpc-java) - RPC framework based on protobuf and HTTP/2.
- [KryoNet](https://github.com/EsotericSoftware/kryonet) - Provides a clean and simple API for efficient TCP and UDP client/server network communication using NIO and Kryo.
- [MINA](https://mina.apache.org) - Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.
- [Netty](https://netty.io) - Framework for building high-performance network applications.
- [ServiceTalk](https://github.com/apple/servicetalk) - Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.
- [Undertow](http://undertow.io) - Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly. (LGPL-2.1-only)
- [urnlib](https://github.com/slub/urnlib) - Represent, parse and encode URNs, as in RFC 2141. (GPL-3.0-only)
- [Apache Cayenne](https://cayenne.apache.org) - Provides a clean, static API for data access. Also includes a GUI Modeler for working with database mappings, and DB reverse engineering and generation.
- [Doma](https://github.com/domaframework/doma) - Database access framework that verifies and generates source code at compile time using annotation processing as well as native SQL templates called two-way SQL.
- [Ebean](https://ebean.io) - Provides simple and fast data access.
- [EclipseLink](https://www.eclipse.org/eclipselink/) - Supports a number of persistence standards: JPA, JAXB, JCA and SDO.
- [Hibernate](http://hibernate.org/orm/) - Robust and widely used, with an active community. (LGPL-2.1-only)
- [MyBatis](https://github.com/mybatis/mybatis-3) - Couples objects with stored procedures or SQL statements.
- [Eclipse BIRT](https://www.eclipse.org/birt) - Report engine for creating PDF and other formats (DOCX, XLSX, HTML, etc) using Eclipse-based visual editor.
- [JMH](http://openjdk.java.net/projects/code-tools/jmh/) - Harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targeting the JVM. (GPL-2.0 only WITH Classpath-exception-2.0)
- [CLI2](http://commons.apache.org/sandbox/commons-cli2/) - Redesign of Commons CLI.
- [Codec](http://commons.apache.org/proper/commons-codec/) - General encoding/decoding algorithms, e.g. phonetic, base64 or URL.
- [Collections](http://commons.apache.org/proper/commons-collections/) - Extends or augments the Java Collections Framework.
- [Compress](http://commons.apache.org/proper/commons-compress/) - Defines an API for working with tar, zip and bzip2 files.
- [Configuration](http://commons.apache.org/proper/commons-configuration/) - Reading of configuration/preferences files in various formats.
- [Convert](http://commons.apache.org/sandbox/commons-convert/) - Commons-Convert aims to provide a single library dedicated to the task of converting an object of one type to another.
- [CSV](http://commons.apache.org/proper/commons-csv/) - Component for reading and writing comma separated value files.
- [Daemon](http://commons.apache.org/proper/commons-daemon/) - Alternative invocation mechanism for unix-daemon-like java code.
- [Email](http://commons.apache.org/proper/commons-email/) - Library for sending e-mail from Java.
- [Exec](http://commons.apache.org/proper/commons-exec/) - API for dealing with external process execution and environment management in Java.
- [FileUpload](http://commons.apache.org/proper/commons-fileupload/) - File upload capability for your servlets and web applications.
- [Finder](http://commons.apache.org/sandbox/commons-finder/) - Java library inspired by the UNIX find command.
- [Flatfile](http://commons.apache.org/sandbox/commons-flatfile/) - Java library for working with flat data structures.
- [Functor](http://commons.apache.org/proper/commons-functor/) - Function that can be manipulated as an object, or an object representing a single, generic function.
- [Graph](http://commons.apache.org/sandbox/commons-graph/) - General purpose graph APIs and algorithms.
- [I18n](http://commons.apache.org/sandbox/commons-i18n/) - Adds the feature of localized message bundles that consist of one or many localized texts that belong together.
- [Id](http://commons.apache.org/sandbox/commons-id/) - Id is a component used to generate identifiers.
- [Jelly](http://commons.apache.org/proper/commons-jelly/) - XML based scripting and processing engine.
- [Jexl](http://commons.apache.org/proper/commons-jexl/) - Expression language which extends the Expression Language of the JSTL.
- [JNet](http://commons.apache.org/sandbox/commons-jnet/) - JNet allows to use dynamically register url stream handlers through the java.net API.
- [JXPath](http://commons.apache.org/proper/commons-jxpath/) - Utilities for manipulating Java Beans using the XPath syntax.
- [Lang](http://commons.apache.org/proper/commons-lang/) - Provides extra functionality for classes in java.lang.
- [Logging](https://commons.apache.org/proper/commons-logging/) - Wrapper around a variety of logging API implementations.
- [Math](http://commons.apache.org/proper/commons-math/) - Lightweight, self-contained mathematics and statistics components.
- [Monitoring](http://commons.apache.org/sandbox/commons-monitoring/) - Monitoring aims to provide a simple but extensible monitoring solution for Java applications.
- [Nabla](http://commons.apache.org/sandbox/commons-nabla/) - Nabla provides automatic differentiation classes that can generate derivative of any function implemented in the Java language.
- [Net](http://commons.apache.org/proper/commons-net/) - Collection of network utilities and protocol implementations.
- [OpenPGP](http://commons.apache.org/sandbox/commons-openpgp/) - Interface to signing and verifying data using OpenPGP.
- [Performance](http://commons.apache.org/sandbox/commons-performance/) - Small framework for microbenchmark clients, with implementations for Commons DBCP and Pool.
- [Pipeline](http://commons.apache.org/sandbox/commons-pipeline/) - Provides a set of pipeline utilities designed around work queues that run in parallel to sequentially process data objects.
- [SCXML](http://commons.apache.org/proper/commons-scxml/) - Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.
- [Validator](http://commons.apache.org/proper/commons-validator/) - Framework to define validators and validation rules in an xml file.
- [VFS](http://commons.apache.org/proper/commons-vfs/) - Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.
- [Weaver](http://commons.apache.org/proper/commons-weaver/) - Provides an easy way to enhance (weave) compiled bytecode.
- [CUBA Platform](https://www.cuba-platform.com/) - High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.
- [Light-4J](https://github.com/networknt/light-4j/) - Fast, lightweight and productive microservices framework with built-in [security](https://github.com/networknt/light-oauth2/).
- [Orienteer](https://github.com/OrienteerBAP/Orienteer/) - Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.
- [Spring](https://spring.io/projects/) - Provides many packages for dependency injection, aspect-oriented programming, security, etc.
- [Akka](https://akka.io) - Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.
- [Reactive Streams](https://github.com/reactive-streams/reactive-streams-jvm) - Provides a standard for asynchronous stream processing with non-blocking backpressure.
- [Dropwizard](https://github.com/dropwizard/dropwizard) - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
- [Elide](https://elide.io) - Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.
- [Microserver](https://github.com/aol/micro-server) - 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](https://www.rapidoid.org) - Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.
- [rest.li](https://github.com/linkedin/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.
- [RestExpress](https://github.com/RestExpress/RestExpress) - Thin wrapper on the JBoss Netty HTTP stack that provides scaling and performance.
- [Restlet Framework](https://github.com/restlet/restlet-framework-java) - Pioneering framework with powerful routing and filtering capabilities, and a unified client and server API.
- [Crnk](http://www.crnk.io) - 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.
- [BioJava](https://biojava.org/) - Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.
- [Chart-FX](https://github.com/GSI-CS-CO/chart-fx) - Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets.
- [Morpheus](https://github.com/zavtech/morpheus-core) - 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.
- [Orson-Charts](https://github.com/jfree/orson-charts) - Generates a wide variety of 3D charts that can be displayed with Swing and JavaFX or exported to PDF, SVG, PNG and JPEG. (GPL-3.0-only)
- [Tablesaw](https://github.com/jtablesaw/tablesaw) - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.
- [Elasticsearch](https://www.elastic.co) - Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.
- [Bouncy Castle](https://www.bouncycastle.org/java.html) - All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.
- [Hdiv](https://github.com/hdiv/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](https://github.com/jwtk/jjwt) - JSON web token for Java and Android.
- [Password4j](https://github.com/Password4j/password4j) - User-friendly cryptographic library that supports Argon2, Bcrypt, Scrypt, PBKDF2 and various other cryptographic hash functions.
- [FlatBuffers](https://github.com/google/flatbuffers) - Memory-efficient serialization library that can access serialized data without unpacking and parsing it.
- [Jetty](https://www.eclipse.org/jetty/) - Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations.
- [Freemarker](https://freemarker.apache.org) - Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.
- [jte](https://github.com/casid/jte) - Compiles to classes and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.
- [Pebble](https://pebbletemplates.io) - 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.
- [StringTemplate](https://github.com/antlr/stringtemplate4) - Template engine for generating source code, web pages, emails, or any other formatted text output.
- [GreenMail](http://www.icegreen.com/greenmail/) - In-memory email server for integration testing. Supports SMTP, POP3 and IMAP including SSL. (GPL-2.0-only)
- [Karate](https://github.com/intuit/karate) - DSL that combines API test-automation, mocks and performance-testing making testing REST/HTTP services easy.
- [JGiven](http://jgiven.org) - Provides a fluent API which allows for simpler composition.
- [Lamdba Behave](https://github.com/RichardWarburton/lambda-behave) - Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.
- [Serenity BDD](https://github.com/serenity-bdd/serenity-core) - Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.
- [Randomized Testing](https://github.com/randomizedtesting/randomizedtesting) - JUnit test runner and plugins for running JUnit tests with pseudo-randomness.
- [Mutability Detector](https://github.com/MutabilityDetector/MutabilityDetector) - Reports whether instances of a given class are immutable.
- [raml-tester](https://github.com/nidi3/raml-tester) - Tests if a request/response matches a given RAML definition.
- [TestContainers](https://github.com/testcontainers/testcontainers-java) - Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.
- [PowerMock](https://github.com/powermock/powermock) - Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.
- [Arthas](https://github.com/alibaba/arthas) - Allows to troubleshoot production issues for applications without modifying code or restarting servers.
- [Embulk](https://github.com/embulk/embulk) - Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.
- [fswatch](https://github.com/vorburger/ch.vorburger.fswatch) - Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.
- [Play](https://www.playframework.com) - Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.
- [Ratpack](https://ratpack.io) - Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications.
- [Takes](https://github.com/yegor256/takes) - Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.
_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._
- [Chris Richardson](https://twitter.com/crichardson) - Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, \*POJOs in Action- author.
- [Josh Long](https://twitter.com/starbuxman) - Spring Advocate at Pivotal, author of O'Reilly's Cloud Native Java- and Building Microservices with Spring Boot, JavaOne Rock Star.
- [Mani Sarkar](https://twitter.com/theNeomatrix369) - Java champion, Polyglot, Software Crafter involved with @graalvm, AI/ML/DL, Data Science, Developer communities, speaker & blogger. Creator of couple of awesome lists like this one.
- [Mario Fusco](https://twitter.com/mariofusco) - RedHatter, JUG coordinator, frequent speaker and author.
- [Mark Heckler](https://twitter.com/MkHeck) - Pivotal Principal Technologist and Developer Advocate, conference speaker, published author, and Java Champion, focusing on Internet of Things and the cloud.
- [Trisha Gee](https://twitter.com/trisha_gee) - Java Champion and speaker.
- [Venkat Subramaniam](https://twitter.com/venkat_s) - Author, University of Houston professor, MicroSoft MVP award recipient, JavaOne Rock Star, Java Champion.
Please have a look at the [CONTRIBUTING](https://github.com/akullpp/awesome-java/blob/master/CONTRIBUTING.md) guidelines and [the validation tools](https://github.com/akullpp/awesome-java-lint).
