Trino - Distributed SQL query engine for big data.
Projects
Distribution
jDeploy - Deploy desktop apps as native Mac, Windows or Linux bundles.
Resources
Podcasts and Screencasts
140 Second Ducklings - Short videos on Twitter explaining Java debugging in depth.
Projects
Configuration
Externalized Propertiesstars14 - Lightweight but powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism.
May 2nd - May 8th, 2022
Projects
Date and Time
Jollydaystars170 - Determines the holidays for a given year, country/name and eventually state/region.
Mar 14th - Mar 20th, 2022
Projects
Logging
Echopraxiastars37 - API designed around structured logging, rich context, and conditional logging. There are Logback and Log4J2 implementations, but Echopraxia's API is completely dependency-free, meaning it can be implemented with any logging API.
Feb 14th - Feb 20th, 2022
Projects
Miscellaneous
RR4Jstars13 - RR4J is a tool that records java bytecode execution and later allows developers to replay locally.
Projects
Code Generators
JPA Buddy - Plugin for IntelliJ IDEA. Provides visual tools for generating JPA entities, Spring Data JPA repositories, Liquibase changelogs and SQL scripts. Offers automatic Liquibase/Flyway script generation by comparing model to DB, and reverse engineering JPA entities from DB tables.
Gecistars107 - Discovers files that need generated code, updates automatically and writes to the source with a convenient API.
Projects
Security
jwt-javastars7 - Easily create and parse JSON Web Tokens and create customized JWT validators using a fluent API.
Nov 8th - Nov 14th, 2021
Resources
Other
Groundbreakers - Oracle ACEs, Groundbreaker Ambassadors and Java Champions.
Projects
Template Engine
Jamalstars18 - Extendable template engine embedded into Maven/JavaDoc, supporting multiple extensions (Groovy, Ruby, JavaScript, JShell, PlantUml) with support for snippet handling.
jtestars394 - Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.
Litiengine - AWT-based, lightweight 2D game engine.
Dec 14th - Dec 20th, 2020
Projects
Computer Vision
BoofCV - Library for image processing, camera calibration, tracking, SFM, MVS, 3D vision, QR Code and much more.
Projects
Miscellaneous
jsweetstars1.3k - Source transpiler to TypeScript/JavaScript.
Dec 7th - Dec 13th, 2020
Projects
Computer Vision
ImageJ - Medical image processing application with an API.
JavaCVstars6k - Java interface to OpenCV, FFmpeg, and much more.
Nov 16th - Nov 22nd, 2020
Projects
HTTP Clients
Google HTTP Clientstars1.2k - Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf.
Projects
Distribution
Getdownstars455 - A system for deploying Java applications to end-user computers and keeping them up to date. Developed as an alternative to Java Web Start.
JavaPackagerstars547 - 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.
Configuratestars240 - Configuration library with support for various configuration formats and transformations.
Oct 12th - Oct 18th, 2020
Projects
Networking
sshjstars2.1k - Programmatically use SSH, SCP or SFTP.
Sep 28th - Oct 4th, 2020
Projects
Science
BioJava - Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.
Mani Sarkar - Java champion, Polyglot, Software Crafter involved with @graalvm, AI/ML/DL, Data Science, Developer communities, speaker & blogger. Creator of couple of awesome lists like this one.
oj! Algorithms - High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing.
Tribuo - Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.
DJL - High-level and engine-agnostic framework for deep learning.
Projects
Microservice
ActiveRPC - Lightweight and fast library for complex high-load distributed applications and Memcached-like solutions.
Aparapistars409 - Converts bytecode to OpenCL which allows execution on GPUs.
Projects
Science
Chart-FXstars348 - Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets.
LogicNGstars90 - Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas.
ActiveJ - Lightweight asynchronous framework built from the ground up for developing high-performance web applications.
Projects
Mobile Development
Codename One - Cross-platform solution for writing native mobile apps. (GPL-2.0-only WITH Classpath-exception-2.0)
MobileUI - Cross-platform framework for developing mobile apps with native UI in Java and Kotlin.
Multi-OS Engine - Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.
Projects
Code Generators
Telosys - Simple and light code generator available as an Eclipse Plugin and also as a CLI.
Projects
Configuration
microconfig - Configuration system designed for microservices which helps to separate configuration from code. The configuration for different services can have common and specific parts and can be dynamically distributed.
Projects
Job Scheduling
easy-batchstars553 - 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.
shedlockstars2.5k - 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.
May 18th - May 24th, 2020
Projects
Game Development
Mini2Dx - Beginner-friendly, master-ready framework for rapidly prototyping and building 2D games.
Projects
Database
Debezium - Low latency data streaming platform for change data capture.
Projects
Job Scheduling
JobRunrstars1k - 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.
Projects
Configuration
configstars5.7k - Configuration library supporting Java properties, JSON or its human optimized superset HOCON.
May 4th - May 10th, 2020
Projects
Imagery
image-comparisonstars214 - 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.
Apr 20th - Apr 26th, 2020
Projects
PDF
Eclipse BIRT - Report engine for creating PDF and other formats (DOCX, XLSX, HTML, etc) using Eclipse-based visual editor.
Projects
Template Engine
Freemarker - Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.
Apr 6th - Apr 12th, 2020
Projects
Hypermedia Types
hatestars20 - Builds hypermedia-friendly objects according to HAL specification.
Mar 30th - Apr 5th, 2020
Projects
JVM and JDK
Dragonwell8stars3.6k - Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.
Mar 23rd - Mar 29th, 2020
Projects
Microservice
Sentinelstars19.3k - Flow control component enabling reliability, resilience and monitoring for microservices.
Projects
Utility
Arthasstars29.5k - Allows to troubleshoot production issues for applications without modifying code or restarting servers.
Projects
Development
Tail - Enable infinite recursion using tail call optimization.
Mar 9th - Mar 15th, 2020
Projects
Distribution
Cloudsmith - Fully managed package management SaaS with support for Maven/Gradle/SBT with a free tier.
Quasar - Lightweight threads and actors for the JVM.
ScaleCube Services - Embeddable Cluster-Membership library based on SWIM and gossip protocol.
Zuulstars12k - Gateway service that provides dynamic routing, monitoring, resiliency, security, and more.
Projects
Functional Programming
Cyclopsstars1.2k - Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.
Vavr - Functional component library that provides persistent data types and functional control structures.
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.
Projects
JSON
Genson - Powerful and easy-to-use Java-to-JSON conversion library.
Yassonstars180 - Binding layer between classes and JSON documents similar to JAXB.
Corretto - No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)
Liberica JDK - Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)
SAP Machine - SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)
Zulu - OpenJDK builds for Windows, Linux, and macOS. (GPL-2.0-only WITH Classpath-exception-2.0)
Projects
Logging
Apache Log4j 2 - Complete rewrite with a powerful plugin and configuration architecture.
Kibana - Analyzes and visualizes log files. Some features require payment.
Logback - Robust logging library with interesting configuration options via Groovy.
tinylog - Lightweight logging framework with static logger class.
OpenTracing Toolboxstars181 - Collection of libraries that build on top of OpenTracing and provide extensions and plugins to existing instrumentations.
Failsafe Actuatorstars52 - Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.
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.
Metricsstars7.6k - Expose metrics via JMX or HTTP and send them to a database.
Projects
Natural Language Processing
LingPipe - Toolkit for tasks ranging from POS tagging to sentiment analysis.
Grizzly - NIO framework. Used as a network layer in Glassfish.
Driftstars213 - Easy-to-use, annotation-based library for creating Thrift clients and serializable types.
Projects
ORM
Domastars323 - 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.
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.
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)
Orienteerstars181 - 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.
Projects
Reactive libraries
Reactorstars4.2k - Library for building reactive fast-data applications.
Projects
REST Frameworks
Dropwizardstars8.2k - Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.
Elide - Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.
Microserverstars933 - 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.
RESTEasy - Fully certified and portable implementation of the JAX-RS specification.
Rapidoid - Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.
Projects
Science
DataMelt - Environment for scientific computation, data analysis and data visualization. (GPL-3.0-or-later)
JFreeChart - 2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)
Morpheusstars219 - 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.
Tablesawstars2.9k - Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.
XChartstars1.3k - Light-weight library for plotting data. Many customizable chart types are available.
Projects
Search
Apache Solr - Enterprise search engine optimized for high-volume traffic.
Projects
Server
Jetty - Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations.
WildFly - Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)
Projects
Template Engine
Handlebars.java - Logicless and semantic Mustache templates.
Thymeleaf - Aims to be a substitute for JSP and works for XML files.
Cukes-RESTstars98 - Collection of Gherkin steps for REST-service testing using Cucumber.
JBehave - Extensively configurable framework that describes stories.
Serenity BDDstars633 - Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.
Modalitystars10 - Lightweight ORM with database reverse engineering features.
eXiststars349 - NoSQL document database and application platform. (LGPL-2.1-only)
Redissonstars19.3k - Allows for distributed and scalable data structures on top of a Redis server.
requerystars3.1k - 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.
Projects
Bean Mapping
JMapperstars194 - Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.
ModelMapperstars2k - Intelligent object mapping library that automatically maps objects to each other.
Projects
Build
Bazel - Tool from Google that builds code quickly and reliably.
Projects
Bytecode Manipulation
ASM - All-purpose, low-level bytecode manipulation and analysis.
Byte Buddy - Further simplifies bytecode generation with a fluent API.
Infinispan - Highly concurrent key/value datastore used for caching.
Projects
CLI
JOpt Simple - Fluent parser that uses the POSIX#getopt and GNU#getopt_long syntaxes.
picocli - ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.
Projects
Code Coverage
Clover - Relies on source-code instrumentation instead of bytecode instrumentation.
Cobertura - Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)
JaCoCo - Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.
Daikon - Detects likely program invariants and generates JML specs based on those invariants.
JMLOK 2.0 - Detects inconsistencies between code and JML specification through feedback-directed random tests generation, and suggests a likely cause for each nonconformance detected. (GPL-3.0-only)
KeY - Formal software development tool that aims to integrate design, implementation, formal specification, and formal verification of object-oriented software as seamlessly as possible. Uses JML for specification and symbolic execution for verification. (GPL-2.0-or-later)
OpenJML - Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)
Chris Richardson - Software architect, consultant, and serial entrepreneur, Java Champion, JavaOne Rock Star, *POJOs in Action- author.
Nov 18th - Nov 24th, 2019
Projects
JVM and JDK
Adopt Open JDK - Community-driven OpenJDK builds, including both HotSpot and OpenJ9.
Open JDK - Open JDK community home. (GPL-2.0-only WITH Classpath-exception-2.0)
Nov 4th - Nov 10th, 2019
Projects
Networking
ServiceTalkstars753 - Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.
Projects
Database
druid - High-performance, column-oriented, distributed data store.
Projects
Introspection
Objenesis - Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions.
Resources
Twitter
Vlad Mihalcea - Java Champion working on Hypersistence Optimizer, database aficionado, author of High-Performance Java Persistence book.
Spencer Gibb - Software Engineer, Dad, Geek, Co-founder and Lead of Spring Cloud Core @pivotal.
Projects
IDE
jGRASP - Created to provide software visualizations that work in conjunction with the debugger such as Control Structure Diagrams, UML class diagrams and Object Viewer.
Projects
Bytecode Manipulation
Persesstars57 - Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.
Projects
Bean Mapping
reMapstars97 - Lambda and method handle-based mapping which requires code and not annotations if objects have different names.
Oct 14th - Oct 20th, 2019
Projects
Introspection
ClassGraphstars2.2k - ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.
ReflectASMstars1.3k - ReflectASM is a very small Java library that provides high performance reflection by using code generation.
Reflectionsstars4.2k - 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.
Checker Framework - Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)
derive4jstars541 - Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms. (GPL-3.0-only)
Projects
Geospatial
GeoTools - Library that provides tools for geospatial data. (LGPL-2.1-only)
Mapsforgestars974 - Map rendering based on OpenStreetMap data. (LGPL-3.0-only)
Projects
JVM and JDK
Graalstars17.2k - Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)
ParparVM - VM with non-blocking, concurrent GC for iOS. (GPL-2.0-only WITH Classpath-exception-2.0)
RedHat Open JDK - RedHat's OpenJDK distribution. (GPL-2.0-only WITH Classpath-exception-2.0)
Projects
Logging
Graylog - Open-source aggregator suited for extended role and permission management. (GPL-3.0-only)
Projects
Machine Learning
JSATstars739 - Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)
Projects
Miscellaneous
FizzBuzz Enterprise Editionstars17.5k - No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)