- [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.
- [Apache Mesos](https://mesos.apache.org) - Abstracts CPU, memory, storage, and other compute resources away from machines.
- [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.
- [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.
- [SBE](https://github.com/real-logic/simple-binary-encoding) - Simple Binary Encoding, one of the fastest message formats around.
- [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)
- [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.
- [IzPack](http://izpack.org) - Setup authoring tool for cross-platform deployments.
- [docx4j](https://www.docx4java.org/trac/docx4j) - Create and manipulate Microsoft Open XML files.
- [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-react](https://github.com/aol/cyclops-react) - 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.
- [Geotoolkit.org](http://www.geotoolkit.org) - Library for developing geospatial applications. Built on top of the Apache SIS project. (LGPL-2.1-only)
- [GeoTools](https://geotools.org) - Library that provides tools for geospatial data. (LGPL-2.1-only)
- [Eclipse](https://www.eclipse.org) - Established open-source project with support for lots of plugins and languages.
- [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) - Compares two images with the same sizes and shows the differences visually by drawing rectangles.
- [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.
- [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.
- [DSL-JSON](https://github.com/ngs-doo/dsl-json) - JSON library with advanced compile time databinding.
- [Genson](https://owlike.github.io/genson) - Powerful and easy-to-use Java-to-JSON conversion library.
- [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.
- [Yasson](https://github.com/eclipse/yasson) - Binding layer between classes and JSON documents similar to JAXB.
- [fastjson](https://github.com/alibaba/fastjson) - Very fast processor with no additional dependencies and full data binding.
- [Jolt](https://github.com/bazaarvoice/jolt) - JSON to JSON transformation tool.
- [JsonPath](https://github.com/jayway/JsonPath) - Extract data from JSON using XPATH-like syntax.
- [JsonSurfer](https://github.com/jsurfer/JsonSurfer) - Streaming JsonPath processor dedicated to processing big and complicated JSON data.
- [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)
- [Graal](https://github.com/oracle/graal) - Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)
- [Liberica JDK](https://www.bell-sw.com/java.html) - Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)
- [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)
- [JSAT](https://github.com/EdwardRaff/JSAT) - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)
- [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.
- [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)
- [Apollo](https://spotify.github.io/apollo) - Libraries for writing composable microservices.
- [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.
- [Lagom](https://www.lightbend.com/lagom) - Framework for creating microservice-based systems.
- [Micronaut](http://micronaut.io) - Modern full-stack framework with focus on modularity, minimal memory footprint and startup time.
- [Nacos](https://nacos.io) - Dynamic service discovery, configuration and service management platform for building cloud native applications.
- [Quarkus](https://quarkus.io) - Kubernetes stack tailored for the HotSpot and Graal VM.
- [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.
- [Smooks](https://github.com/smooks/smooks) - Extensible framework for building applications that process data which means bindings, transformations, message processing and enrichment. (LGPL-3.0-only)
- [Failsafe Actuator](https://github.com/zalando-incubator/failsafe-actuator) - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
- [inspectIT](http://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.
- [Prometheus](https://prometheus.io) - Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.
- [SPM ![c]](https://sematext.com/spm) - Performance monitor with distributing transaction tracing for JVM apps.
- [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)
- [Finagle](https://github.com/twitter/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](https://javaee.github.io/grizzly) - NIO framework. Used as a network layer in Glassfish.
- [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.
- [Nifty](https://github.com/facebook/nifty) - Implementation of Thrift clients and servers on Netty.
- [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 2](https://doma.readthedocs.io) - 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.
- [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)
- [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.
- [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.
- [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.
- [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://cuba-platform.com) - High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.
- [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.
- [Reactor](https://projectreactor.io) - Library for building reactive fast-data applications.
- [RxJava](https://github.com/ReactiveX/RxJava) - Allows for composing asynchronous and event-based programs using observable sequences.
- [Dropwizard](https://dropwizard.github.io/dropwizard) - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
- [javalin](https://javalin.io) - Javalin is just a few thousand lines of code on top of Jetty, which means its performance is almost equivalent to pure Jetty.
- [Microserver](https://github.com/aol/micro-server) - 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](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.
- [RESTEasy](https://resteasy.jboss.org) - Fully certified and portable implementation of the JAX-RS specification.
- [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.
- [JGraphT](https://github.com/jgrapht/jgrapht) - Graph library that provides mathematical graph-theory objects and algorithms.
- [JGraphX](https://github.com/jgraph/jgraphx) - Library for visualizing (mainly Swing) and interacting with node-edge graphs.
- [Mines Java Toolkit](https://github.com/MinesJTK/jtk) - Library for geophysical scientific computation, visualization and digital signal analysis.
- [Morpheus](http://www.zavtech.com/morpheus/docs) - 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/lwhite1/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.
- [Vault](https://www.vaultproject.io) - 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.
- [FlatBuffers](https://github.com/google/flatbuffers) - Memory-efficient serialization library that can access serialized data without unpacking and parsing it.
- [Apache Tomcat](https://tomcat.apache.org) - Robust, all-round server for Servlet and JSP.
- [Apache TomEE](https://tomee.apache.org) - Tomcat plus Java EE.
- [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.
- [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.
- [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 combine API test-automation, mocks and performance-testing making testing REST/HTTP services easy.
- [J8Spec](https://github.com/j8spec/j8spec) - Follows a Jasmine-like syntax.
- [JBehave](http://jbehave.org) - Extensively configurable framework that describes stories.
- [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://www.thucydides.info) - 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.
- [Mockito](https://github.com/mockito/mockito) - Mocking framework that lets you write tests with a clean and simple API.
- [MockServer](https://www.mock-server.com) - Allows mocking of systems integrated with HTTPS.
- [Moco](https://github.com/dreamhead/moco) - Concise web services for stubs and mocks.
- [PowerMock](https://github.com/jayway/powermock) - Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.
- [WireMock](http://wiremock.org) - Stubs and mocks web services.
- [fswatch](https://github.com/vorburger/ch.vorburger.fswatch) - Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.
- [jabba](https://github.com/shyiko/jabba) - Java Version Manager inspired by nvm. Supports macOS, Linux and Windows.
- [jenv](https://github.com/gcuisinier/jenv) - Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and macOS.
- [Firefly](http://www.fireflysource.com) - Asynchronous framework for rapid development of high-performance web application.
- [Grails](https://grails.org) - Groovy framework that provides a highly productive environment by favoring convention over configuration, no XML and support for mixins.
- [Jooby](http://jooby.org) - Scalable, fast and modular micro-framework that offers multiple programming models.
- [Ninja](http://www.ninjaframework.org) - Full-stack web framework.
- [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.
- [PrimeFaces](https://primefaces.org) - JSF framework with both free and commercial/support versions and frontend components.
- [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.
- [Vaadin Flow](https://vaadin.com/flow) - Event-driven framework that uses standard web components. Server-side architecture with Ajax on the client side.
_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.
- [Lukas Eder](https://twitter.com/lukaseder) - Java Champion, speaker, JUG.ch co-leader, Founder and CEO Data Geekery (jOOQ).
- [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-validation).
