Awesome Java Projects

This is a list of repositories sorted by GitHub stars.

Bean Mapping

Frameworks that ease bean mapping.

6939 Stars

MapStruct

Code generator that simplifies mappings between different bean types, based on a convention-over-configuration approach.

2257 Stars

ModelMapper

Intelligent object mapping library that automatically maps objects to each other.

1289 Stars

Orika

JavaBean-mapping framework that recursively copies (among other capabilities) data from one object to another.

226 Stars

JMapper

Uses byte code manipulation for lightning-fast mapping. Supports annotations and API or XML configuration.

210 Stars

Selma

Annotation processor-based bean mapper.

117 Stars

reMap

Lambda and method handle-based mapping which requires code and not annotations if objects have different names.

89 Stars

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.

Build

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

22744 Stars

Bazel

Tool from Google that builds code quickly and reliably.

16448 Stars

Gradle

Incremental builds programmed via Groovy instead of declaring XML. Works well with Maven's dependency management.

8560 Stars

Buck

Encourages the creation of small, reusable modules consisting of code and resources.

4238 Stars

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.

Bytecode Manipulation

Libraries to manipulate bytecode programmatically.

14480 Stars

bytecode-viewer

Java 8 Jar & Android APK reverse engineering suite. (GPL-3.0-only)

6108 Stars

Byte Buddy

Further simplifies bytecode generation with a fluent API.

5795 Stars

Recaf

JVM reverse engineering toolkit, essentially an IDE for Java bytecode.

4766 Stars

cglib

Bytecode generation library.

4060 Stars

Javassist

Tries to simplify bytecode editing.

1359 Stars

Mixin

Manipulate bytecode at runtime using real Java code.

477 Stars

Byteman

Manipulate bytecode at runtime via DSL (rules); mainly for testing/troubleshooting. (LGPL-2.1-or-later)

65 Stars

Perses

Dynamically injects failure/latency at the bytecode level according to principles of chaos engineering.

50 Stars

Maker

Provides low level bytecode generation.

Caching

Libraries that provide caching facilities.

15511 Stars

Caffeine

High-performance, near-optimal caching library.

1984 Stars

Ehcache

Distributed general-purpose cache.

1160 Stars

Infinispan

Highly concurrent key/value datastore used for caching.

704 Stars

cache2k

In-memory high performance caching library.

CLI

Libraries for everything related to the CLI.

4805 Stars

picocli

ANSI colors and styles in usage help with annotation-based POSIX/GNU/any syntax, subcommands, strong typing for both options and positional args.

2234 Stars

Lanterna

Easy console text-GUI library, similar to curses. (LGPL-3.0-only)

1936 Stars

JCommander

Command-line argument-parsing framework with custom types and validation via implementing interfaces.

1419 Stars

JLine

Includes features from modern shells like completion or history.

1101 Stars

Jansi

ANSI escape codes to format console output.

846 Stars

Airline

Annotation-based framework for parsing Git-like command-line arguments.

784 Stars

args4j

Small library to parse command-line arguments.

484 Stars

ASCII Table

Library to draw tables in ASCII.

346 Stars

JOpt Simple

Fluent parser that uses the POSIX#getopt and GNU#getopt_long syntaxes.

338 Stars

Text-IO

Aids the creation of full console-based applications.

156 Stars

Java ASCII Render

Graphical primitives for the console.

82 Stars

jbock

Reflectionless command line parser.

Cluster Management

Frameworks that can dynamically manage applications inside of a cluster.

822 Stars

Singularity

Mesos framework that makes deployment and operations easy. It supports web services, background workers, scheduled jobs, and one-off tasks.

632 Stars

Apache Aurora

Mesos framework for long-running services and cron jobs.

Code Analysis

Tools that provide metrics and quality measurements.

30264 Stars

p3c

Provides Alibaba's coding guidelines for PMD, IDEA and Eclipse.

14808 Stars

Infer

Modern static analysis tool for verifying the correctness of code.

8239 Stars

Checkstyle

Static analysis of coding conventions and standards. (LGPL-2.1-or-later)

6776 Stars

Error Prone

Catches common programming mistakes as compile-time errors.

4733 Stars

PMD

Source code analysis for finding bad coding practices.

3595 Stars

NullAway

Eliminates NullPointerExceptions with low build-time overhead.

3400 Stars

Spotbugs

Static analysis of bytecode to find potential bugs. (LGPL-2.1-only)

1712 Stars

Spoon

Library for analyzing and transforming Java source code.

1101 Stars

SonarJava

Static analyzer for SonarQube & SonarLint. (LGPL-3.0-only)

352 Stars

RefactorFirst

Identifies and prioritizes God Classes and Highly Coupled classes.

189 Stars

jQAssistant

Static code analysis with Neo4J-based query language. (GPL-3.0-only)

179 Stars

Error Prone Support

Error Prone extensions: extra bug checkers and a large battery of Refaster templates.

Code Coverage

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

4093 Stars

JaCoCo

Framework that enables collection of code coverage metrics, using both offline and runtime bytecode instrumentation.

1022 Stars

Cobertura

Relies on offline (or static) bytecode instrumentation and class loading to collect code coverage metrics. (GPL-2.0-only)

57 Stars

Clover

Relies on source-code instrumentation instead of bytecode instrumentation.

Code Generators

Tools that generate patterns for repetitive code in order to reduce verbosity and error-proneness.

21344 Stars

JHipster

Yeoman source code generator for Spring Boot and AngularJS.

12726 Stars

Lombok

Code generator that aims to reduce verbosity.

10752 Stars

JavaPoet

API to generate source files.

10406 Stars

Auto

Generates factory, service, and value classes.

3403 Stars

Immutables

Annotation processors to generate simple, safe and consistent value objects.

828 Stars

FreeBuilder

Automatically generates the Builder pattern.

676 Stars

Record-Builder

Companion builder class, withers and templates for Java records.

155 Stars

Telosys

Simple and light code generator available as an Eclipse Plugin and also as a CLI.

143 Stars

ADT4J

JSR-269 code generator for algebraic data types.

142 Stars

Joda-Beans

Small framework that adds queryable properties to Java, enhancing JavaBeans.

129 Stars

Geci

Discovers files that need generated code, updates automatically and writes to the source with a convenient API.

62 Stars

Avaje Http Server

Generates Lightweight JAX-RS style http servers using Javalin or Helidon (Nima) SE.

0 Stars

JPA Buddy ![c]

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.

Compiler-compiler

Frameworks that help to create parsers, interpreters or compilers.

16736 Stars

ANTLR

Complex full-featured framework for top-down parsing.

1152 Stars

JavaCC

Parser generator that generates top-down parsers. Allows lexical state switching and permits extended BNF specifications.

579 Stars

JFlex

Lexical analyzer generator.

Computer Vision

Libraries which seek to gain high level information from images and videos.

7429 Stars

JavaCV

Java interface to OpenCV, FFmpeg, and much more.

1055 Stars

BoofCV

Library for image processing, camera calibration, tracking, SFM, MVS, 3D vision, QR Code and much more.

515 Stars

ImageJ

Medical image processing application with an API.

Configuration

Libraries that provide external configuration.

6118 Stars

config

Configuration library supporting Java properties, JSON or its human optimized superset HOCON.

3087 Stars

Curator Framework

High-level API for Apache ZooKeeper.

911 Stars

owner

Reduces boilerplate of properties.

589 Stars

centraldogma

Highly-available version-controlled service configuration repository based on Git, ZooKeeper and HTTP/2.

554 Stars

cfg4j

Modern configuration library for distributed apps written in Java.

357 Stars

Configurate

Configuration library with support for various configuration formats and transformations.

301 Stars

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.

59 Stars

KAConf

Annotation-based configuration system for Java and Kotlin.

47 Stars

avaje config

Loads yaml and properties files, supports dynamic configuration, plugins, file-watching and config event listeners.

46 Stars

dotenv

Twelve-factor configuration library which uses environment-specific files.

26 Stars

Externalized Properties

Lightweight yet powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism.

Constraint Satisfaction Problem Solver

Libraries that help with implementing optimization and satisfiability problems.

823 Stars

Timefold

Flexible solver with Spring/Quarkus support and quickstarts for the Vehicle Routing Problem, Maintenance Scheduling, Employee Shift Scheduling and much more.

683 Stars

Choco

Off-the-shelf constraint satisfaction problem solver that uses constraint programming techniques.

219 Stars

JaCoP

Includes an interface for the FlatZinc language, enabling it to execute MiniZinc models. (AGPL-3.0)

186 Stars

OptaPlanner

Business planning and resource scheduling optimization solver.

CSV

Frameworks and libraries that simplify reading/writing CSV data.

899 Stars

uniVocity-parsers

One of the fastest and most feature-complete parsers. Also comes with parsers for TSV and fixed-width records.

524 Stars

FastCSV

Performance-optimized, dependency-free and RFC 4180 compliant.

522 Stars

Super CSV

Powerful CSV parser with support for Dozer, Joda-Time and Java 8.

194 Stars

jackson-dataformat-csv

Jackson extension for reading and writing CSV.

Data Structures

Efficient and specific data structures.

64647 Stars

Protobuf

Google's data interchange format.

10245 Stars

Apache Thrift

Data interchange format that originated at Facebook.

4216 Stars

Wire

Clean, lightweight protocol buffers.

3448 Stars

RoaringBitmap

Fast and efficient compressed bitmap.

3050 Stars

SBE

Simple Binary Encoding, one of the fastest message formats around.

2832 Stars

Apache Avro

Data interchange format with dynamic typing, untagged data, and absence of manually assigned IDs.

2466 Stars

Tape

Lightning-fast, transactional, file-based FIFO.

760 Stars

Persistent Collection

Persistent and immutable analogue of the Java Collections Framework.

670 Stars

Apache Orc

Fast and efficient columnar storage format for Hadoop-based workloads.

553 Stars

Big Queue

Fast and persistent queue based on memory-mapped files.

53 Stars

HyperMinHash-java

Probabilistic data structure for computing union, intersection, and set cardinality in loglog space.

0 Stars

Apache Parquet

Columnar storage format based on assembly algorithms from Google's paper on Dremel.

Database

Everything that simplifies interactions with the database.

23007 Stars

Redisson

Allows for distributed and scalable data structures on top of a Redis server.

19682 Stars

HikariCP

High-performance JDBC connection pool.

14047 Stars

QuestDB

High-performance SQL database for time series. Supports InfluxDB line protocol, PostgreSQL wire protocol, and REST.

13315 Stars

druid

High-performance, column-oriented, distributed data store.

11711 Stars

Jedis

Small client for interaction with Redis, with methods for commands.

11449 Stars

Realm

Mobile database to run directly inside phones, tablets or wearables.

10200 Stars

Debezium

Low latency data streaming platform for change data capture.

9927 Stars

Trino

Distributed SQL query engine for big data.

7954 Stars

Flyway

Simple database migration tool.

6358 Stars

Leaf

Distributed ID generate service.

6038 Stars

jOOQ

Generates typesafe code based on SQL schema.

4872 Stars

MapDB

Embedded database engine that provides concurrent collections backed on disk or in off-heap memory.

4668 Stars

Querydsl

Typesafe unified queries.

4530 Stars

Liquibase

Database-independent library for tracking, managing and applying database schema changes.

4469 Stars

Apache Calcite

Dynamic data management framework. It contains many of the pieces that comprise a typical database management system.

4124 Stars

H2

Small SQL database notable for its in-memory functionality.

3132 Stars

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.

2739 Stars

Chronicle Map

Efficient, in-memory (opt. persisted to disk), off-heap key-value store.

2113 Stars

Jest

Client for the Elasticsearch REST API.

2091 Stars

Speedment

Database access library that utilizes Java 8's Stream API for querying.

1939 Stars

JDBI

Convenient abstraction of JDBC.

1925 Stars

Apache Drill

Distributed, schema on-the-fly, ANSI SQL query engine for Big Data exploration.

1177 Stars

Xodus

Highly concurrent transactional schema-less and ACID-compliant embedded database.

1063 Stars

FlexyPool

Brings metrics and failover strategies to the most common connection pooling solutions.

1019 Stars

Apache Phoenix

High-performance relational database layer over HBase for low-latency applications.

658 Stars

Jinq

Typesafe database queries via symbolic execution of Java 8 Lambdas (on top of JPA or jOOQ).

451 Stars

CosId

Universal, flexible, high-performance distributed ID generator.

416 Stars

eXist

NoSQL document database and application platform. (LGPL-2.1-only)

358 Stars

OpenDJ

LDAPv3 compliant directory service, developed for the Java platform, providing a high performance, highly available, and secure store for the identities.

200 Stars

ArangoDB

ArangoDB Java driver.

137 Stars

jetcd

Client library for etcd.

96 Stars

Vibur DBCP

JDBC connection pool library with advanced performance monitoring capabilities.

95 Stars

Spring Data JPA MongoDB Expressions

Allows you to use MongoDB query language to query your relational database.

15 Stars

QueryStream

Build JPA Criteria queries using a Stream-like API.

12 Stars

Modality

Lightweight ORM with database reverse engineering features.

7 Stars

MariaDB4j

Launcher for MariaDB that requires no installation or external dependencies.

0 Stars

Lettuce

Lettuce is a scalable Redis client for building non-blocking Reactive applications.

Date and Time

Libraries related to handling date and time.

739 Stars

iCal4j

Parse and build iCalendar [RFC 5545](https://tools.ietf.org/html/rfc5545) data models.

426 Stars

Time4J

Advanced date and time library. (LGPL-2.1-only)

388 Stars

ThreeTen-Extra

Additional date-time classes that complement those in JDK 8.

186 Stars

Jollyday

Determines the holidays for a given year, country/name and eventually state/region.

Dependency Injection

Libraries that help to realize the [Inversion of Control](https://en.wikipedia.org/wiki/Inversion_of_control) paradigm.

17356 Stars

Dagger

Compile-time injection framework without reflection.

12423 Stars

Guice

Lightweight and opinionated framework that completes Dagger.

823 Stars

Governator

Extensions and utilities that enhance Google Guice.

351 Stars

Feather

Ultra-lightweight, JSR-330-compliant dependency injection library.

214 Stars

Avaje Inject

Microservice-focused compile-time injection framework without reflection.

148 Stars

Apache DeltaSpike

CDI extension framework.

111 Stars

HK2

Lightweight and dynamic dependency injection framework.

55 Stars

JayWire

Lightweight dependency injection framework. (LGPL-3.0-only)

Development

Augmentation of the development process at a fundamental level.

5322 Stars

JavaParser

Parse, modify and generate Java code.

2303 Stars

Manifold

Re-energizes Java with powerful features like type-safe metaprogramming, structural typing and extension methods.

2241 Stars

HotswapAgent

Unlimited runtime class and resource redefinition. (GPL-2.0-only)

1759 Stars

DCEVM

JVM modification that allows unlimited redefinition of loaded classes at runtime. (GPL-2.0-only)

291 Stars

JavaSymbolSolver

Symbol solver.

274 Stars

AspectJ

Seamless aspect-oriented programming extension.

130 Stars

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.

92 Stars

NoException

Allows checked exceptions in functional interfaces and converts exceptions to Optional return.

74 Stars

SneakyThrow

Ignores checked exceptions without bytecode manipulation. Can also be used inside Java 8 stream operations.

23 Stars

Tail

Enable infinite recursion using tail call optimization.

Distributed Applications

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

13322 Stars

Zuul

Gateway service that provides dynamic routing, monitoring, resiliency, security, and more.

12062 Stars

Apache ZooKeeper

Coordination service with distributed configuration, synchronization, and naming registry for large distributed systems.

9565 Stars

resilience4j

Functional fault tolerance library.

6573 Stars

Apache Storm

Realtime computation system.

5998 Stars

Hazelcast

Highly scalable in-memory datagrid with a free open-source version.

4557 Stars

Quasar

Lightweight threads and actors for the JVM.

4144 Stars

Failsafe

Simple failure handling with retries and circuit breakers.

2350 Stars

Atomix

Fault-tolerant distributed coordination framework.

2279 Stars

Apache Geode

In-memory data management system that provides reliable asynchronous event notifications and guaranteed message delivery.

1011 Stars

JGroups

Toolkit for reliable messaging and cluster creation.

605 Stars

ScaleCube Services

Embeddable Cluster-Membership library based on SWIM and gossip protocol.

67 Stars

OpenIG

High-performance reverse proxy server with specialized session management and credential replay functionality.

41 Stars

Dropwizard Circuit Breaker

Circuit breaker design pattern for Dropwizard. (GPL-2.0-only)

Distributed Transactions

Distributed transactions provide a mechanism for ensuring consistency of data updates in the presence of concurrent access and partial failures.

454 Stars

Atomikos

Provides transactions for REST, SOA and microservices with support for JTA and XA.

230 Stars

Narayana

Provides support for traditional ACID and compensation transactions, also complies with JTA, JTS and other standards. (LGPL-2.1-only)

0 Stars

Bitronix

Simple but complete implementation of the JTA 1.1 API.

0 Stars

Seata

Delivers high performance and easy to use distributed transaction services under a microservices architecture.

Distribution

Tools that handle the distribution of applications in native formats.

2548 Stars

packr

Packs JARs, assets and the JVM for native distribution on Windows, Linux and macOS.

1147 Stars

Capsule

Simple and powerful packaging and deployment. A fat JAR on steroids, or a "Docker for Java" that supports JVM-optimized containers.

1001 Stars

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.

498 Stars

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.

484 Stars

Artipie

Binary artifact management toolkit which hosts them on the file system or S3.

478 Stars

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.

349 Stars

jDeploy

Deploy desktop apps as native Mac, Windows or Linux bundles.

322 Stars

IzPack

Setup authoring tool for cross-platform deployments.

124 Stars

really-executable-jars-maven-plugin

Maven plugin for making self-executing JARs.

45 Stars

jlink.online

Builds optimized runtimes over HTTP.

Document Processing

Libraries that assist with processing office document formats.

2059 Stars

docx4j

Create and manipulate Microsoft Open XML files.

1893 Stars

Apache POI

Supports OOXML (XLSX, DOCX, PPTX) as well as OLE2 (XLS, DOC or PPT).

651 Stars

fastexcel

High performance library to read and write large Excel (XLSX) worksheets.

542 Stars

documents4j

API for document format conversion using third-party converters such as MS Word.

80 Stars

zerocell

Annotation-based API for reading data from Excel sheets into POJOs with focus on reduced overhead.

Financial

Libraries related to the financial domain.

2001 Stars

ta4j

Library for technical analysis.

774 Stars

Stripe

Integration with the Stripe API.

569 Stars

Cassandre

Trading bot framework.

502 Stars

Parity

Platform for trading venues.

320 Stars

Philadelphia

Low-latency financial information exchange.

39 Stars

Square

Integration with the Square API.

Formal Verification

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

999 Stars

Checker Framework

Pluggable type systems. Includes nullness types, physical units, immutability types and more. (GPL-2.0-only WITH Classpath-exception-2.0)

518 Stars

Java Path Finder (JPF)

JVM formal verification tool containing a model checker and more. Created by NASA.

208 Stars

Daikon

Detects likely program invariants and generates JML specs based on those invariants.

136 Stars

OpenJML

Translates JML specifications into SMT-LIB format and passes the proof problems implied by the program to backend solvers. (GPL-2.0-only)

98 Stars

CATG

Concolic unit testing engine. Automatically generates unit tests using formal methods.

42 Stars

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)

4 Stars

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)

Functional Programming

Libraries that facilitate functional programming.

5597 Stars

Vavr

Functional component library that provides persistent data types and functional control structures.

2172 Stars

StreamEx

Enhances Java 8 Streams.

2071 Stars

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.

1594 Stars

Functional Java

Implements numerous basic and advanced programming abstractions that assist composition-oriented development.

1308 Stars

Cyclops

Monad and stream utilities, comprehensions, pattern matching, functional extensions for all JDK collections, future streams, trampolines and much more.

560 Stars

derive4j

Java 8 annotation processor and framework for deriving algebraic data types constructors, pattern-matching and morphisms. (GPL-3.0-only)

480 Stars

protonpack

Collection of stream utilities.

Game Development

Frameworks that support the development of games.

22983 Stars

libGDX

All-round cross-platform, high-level framework.

4681 Stars

LWJGL

Robust framework that abstracts libraries like OpenGL/CL/AL.

4269 Stars

FXGL

JavaFX Game Development Framework.

3746 Stars

jMonkeyEngine

Game engine for modern 3D development.

1103 Stars

JBox2D

Port of the renowned C++ 2D physics engine.

723 Stars

Litiengine

AWT-based, lightweight 2D game engine.

506 Stars

Mini2Dx

Beginner-friendly, master-ready framework for rapidly prototyping and building 2D games.

0 Stars

Void2D

High-level 2D game engine with built-in physics based on Swing.

Geospatial

Libraries for working with geospatial data and algorithms.

4844 Stars

GraphHopper

Road-routing engine. Used as a Java library or standalone web service.

1676 Stars

GeoTools

Library that provides tools for geospatial data. (LGPL-2.1-only)

1160 Stars

Mapsforge

Map rendering based on OpenStreetMap data. (LGPL-3.0-only)

930 Stars

Spatial4j

General-purpose spatial/geospatial library.

406 Stars

Geo

GeoHash utilities in Java.

203 Stars

H2GIS

Spatial extension of the H2 database. (LGPL-3.0-only)

98 Stars

Apache SIS

Library for developing geospatial applications.

64 Stars

Jgeohash

Library for using the GeoHash algorithm.

GUI

Libraries to create modern graphical user interfaces.

2618 Stars

JavaFX

Successor of Swing.

710 Stars

Scene Builder

Visual layout tool for JavaFX applications.

101 Stars

SWT

Graphical widget toolkit.

High Performance

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

17231 Stars

Disruptor

Inter-thread messaging library.

3521 Stars

JCTools

Concurrency tools currently missing from the JDK.

2776 Stars

Agrona

Data structures and utility methods that are common in high-performance applications.

2389 Stars

Eclipse Collections

Collections framework inspired by Smalltalk.

1739 Stars

fastutil

Fast and compact type-specific collections.

1002 Stars

Koloboke

Carefully designed extension of the Java Collections Framework with primitive specializations and more.

970 Stars

HPPC

Primitive collections.

HTTP Clients

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

42853 Stars

Retrofit

Typesafe REST client.

9356 Stars

Feign

HTTP client binder inspired by Retrofit, JAXRS-2.0, and WebSocket.

6260 Stars

Async Http Client

Asynchronous HTTP and WebSocket client library.

4538 Stars

Ribbon

Client-side IPC library that is battle-tested in the cloud.

2584 Stars

unirest-java

Simplified, lightweight HTTP client library.

1436 Stars

Apache HttpComponents

A toolset of low-level Java components focused on HTTP and associated protocols.

1382 Stars

Google HTTP Client

Pluggable HTTP transport abstraction with support for java.net.HttpURLConnection, Apache HTTP Client, Android, Google App Engine, XML, Gson, Jackson and Protobuf.

293 Stars

Riptide

Client-side response routing for Spring's RestTemplate.

227 Stars

methanol

HTTP client extensions library.

62 Stars

Avaje Http Client

A wrapper on JDK 11's HttpClient that adds Feign-like interface among other enhancements.

Hypermedia Types

Libraries that handle serialization to hypermedia types.

373 Stars

JSON-LD

JSON-LD implementation.

25 Stars

Siren4J

Library for the Siren specification.

22 Stars

hate

Builds hypermedia-friendly objects according to HAL specification.

IDE

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

160782 Stars

Visual Studio Code

Provides Java support for lightweight projects with a simple, modern workflow by using extensions from the internal marketplace.

2601 Stars

NetBeans

Provides integration for several Java SE and EE features, from database access to HTML5.

Imagery

Libraries that assist with the creation, evaluation or manipulation of graphical images.

32491 Stars

ZXing

Multi-format 1D/2D barcode image processing library.

5078 Stars

Thumbnailator

High-quality thumbnail generation library.

1838 Stars

TwelveMonkeys

Collection of plugins that extend the number of supported image file formats.

1561 Stars

Tess4J

JNA wrapper for Tesseract OCR API.

1214 Stars

Imgscalr

Simple, efficient and hardware-accelerated image-scaling library implemented in pure Java 2D.

327 Stars

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.

Introspection

Libraries that help make the Java introspection and reflection API easier and faster to use.

4696 Stars

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.

2793 Stars

jOOR

jOOR stands for jOOR Object Oriented Reflection. It is a simple wrapper for the java.lang.reflect package.

2684 Stars

ClassGraph

ClassGraph (formerly FastClasspathScanner) is an uber-fast, ultra-lightweight, parallelized classpath scanner and module scanner for Java, Scala, Kotlin and other JVM languages.

1512 Stars

ReflectASM

ReflectASM is a very small Java library that provides high performance reflection by using code generation.

590 Stars

Objenesis

Allows dynamic instantiation without default constructor, e.g. constructors which have required arguments, side effects or throw exceptions.

104 Stars

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.

Job Scheduling

Libraries for scheduling background jobs.

6165 Stars

Quartz

Feature-rich, open source job scheduling library that can be integrated within virtually any Java application.

3512 Stars

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.

2286 Stars

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.

1180 Stars

db-scheduler

Persistent and cluster-friendly scheduler.

605 Stars

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.

267 Stars

Sundial

Lightweight framework to simply define jobs, define triggers and start the scheduler.

124 Stars

Wisp

Simple library with minimal footprint and straightforward API.

JSON

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

25691 Stars

fastjson

Very fast processor with no additional dependencies and full data binding.

23149 Stars

Gson

Serializes objects to JSON and vice versa. Good performance with on-the-fly usage.

9626 Stars

Moshi

Modern JSON library, less opinionated and uses built-in types like List and Map.

8954 Stars

Jackson

Similar to GSON, but offers performance gains if you need to instantiate the library more often.

8774 Stars

JsonPath

Extract data from JSON using XPATH-like syntax.

3211 Stars

LoganSquare

JSON parsing and serializing library based on Jackson's streaming API. Outperforms GSON & Jackson's library.

1535 Stars

Jolt

JSON to JSON transformation tool.

1498 Stars

jsoniter

Fast and flexible library with iterator and lazy parsing API.

994 Stars

DSL-JSON

JSON library with advanced compile time databinding.

461 Stars

HikariJSON

High-performance JSON parser, 2x faster than Jackson.

397 Stars

jackson-modules-java8

Set of Jackson modules for Java 8 datatypes and features.

326 Stars

JSON-io

Convert Java to JSON. Convert JSON to Java. Pretty print JSON. Java JSON serializer.

289 Stars

JsonSurfer

Streaming JsonPath processor dedicated to processing big and complicated JSON data.

245 Stars

Jackson-datatype-money

Open-source Jackson module to support JSON serialization and deserialization of JavaMoney data types.

218 Stars

Genson

Powerful and easy-to-use Java-to-JSON conversion library.

198 Stars

Yasson

Binding layer between classes and JSON documents similar to JAXB.

51 Stars

Avaje Jsonb

Reflection-free Json binding via source code generation with Jackson-like annotations.

JVM and JDK

Current implementations of the JVM/JDK.

20013 Stars

Graal

Polyglot embeddable JVM. (GPL-2.0-only WITH Classpath-exception-2.0)

18978 Stars

Open JDK

Open JDK community home. (GPL-2.0-only WITH Classpath-exception-2.0)

4150 Stars

Dragonwell8

Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.

3239 Stars

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.

3040 Stars

Adopt Open JDK

Community-driven OpenJDK builds, including both HotSpot and OpenJ9.

2096 Stars

Corretto

No-cost, multiplatform, production-ready distribution of OpenJDK by Amazon. (GPL-2.0-only WITH Classpath-exception-2.0)

1672 Stars

ParparVM

VM with non-blocking, concurrent GC for iOS. (GPL-2.0-only WITH Classpath-exception-2.0)

1215 Stars

Avian

JVM with JIT, AOT modes and iOS port.

496 Stars

SAP Machine

SAP's no-cost, rigorously tested and JCK-verified OpenJDK friendly fork. (GPL-2.0-only WITH Classpath-exception-2.0)

297 Stars

Liberica JDK

Built from OpenJDK, thoroughly tested and passed the JCK. (GPL-2.0-only WITH Classpath-exception-2.0)

260 Stars

Zulu

OpenJDK builds for Windows, Linux, and macOS. (GPL-2.0-only WITH Classpath-exception-2.0)

Logging

Libraries that log the behavior of an application.

19495 Stars

Kibana

Analyzes and visualizes log files. Some features require payment.

14100 Stars

Logstash

Tool for managing log files.

7235 Stars

Graylog

Open-source aggregator suited for extended role and permission management. (GPL-3.0-only)

3313 Stars

Apache Log4j 2

Complete rewrite with a powerful plugin and configuration architecture.

2937 Stars

Logback

Robust logging library with interesting configuration options via Groovy.

2295 Stars

SLF4J

Abstraction layer/simple logging facade.

2028 Stars

p6spy

Enables logging for all JDBC transactions without changes to the code.

1780 Stars

Logbook

Extensible, open-source library for HTTP request and response logging.

683 Stars

tinylog

Lightweight logging framework with static logger class.

181 Stars

OpenTracing Toolbox

Collection of libraries that build on top of OpenTracing and provide extensions and plugins to existing instrumentations.

54 Stars

Echopraxia

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.

Machine Learning

Tools that provide specific statistical algorithms for learning from data.

23541 Stars

Apache Flink

Fast, reliable, large-scale data processing engine.

13538 Stars

Deeplearning4j

Distributed and multi-threaded deep learning library.

11017 Stars

H2O ![c]

Analytics engine for statistics over big data.

5974 Stars

Smile

Statistical Machine Intelligence and Learning Engine provides a set of machine learning algorithms and a visualization library.

3997 Stars

DJL

High-level and engine-agnostic framework for deep learning.

2748 Stars

m2cgen

CLI tool to transpile models into native code.

2129 Stars

Apache Mahout

Scalable algorithms focused on collaborative filtering, clustering and classification.

1788 Stars

Oryx 2

Framework for building real-time, large-scale machine learning applications. Includes end-to-end applications for collaborative filtering, classification, regression, and clustering.

1508 Stars

Siddhi

Cloud native streaming and complex event processing engine.

1248 Stars

Tribuo

Provides tools for classification, regression, clustering, model development and interfaces with other libraries such as scikit-learn, pytorch and TensorFlow.

1086 Stars

DatumBox

Provides several algorithms and pre-trained models for natural language processing.

786 Stars

JSAT

Algorithms for pre-processing, classification, regression, and clustering with support for multi-threaded execution. (GPL-3.0-only)

458 Stars

oj! Algorithms

High-performance mathematics, linear algebra and optimisation needed for data science, machine learning and scientific computing.

178 Stars

Weka

Collection of algorithms for data mining tasks ranging from pre-processing to visualization. (GPL-3.0-only)

64 Stars

Intelligent java

Seamlessly integrate with remote deep learning and language models programmatically.

Messaging

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

27948 Stars

Apache Kafka

High-throughput distributed messaging system.

24637 Stars

EventBus

Simple publish/subscribe event bus.

20827 Stars

Apache RocketMQ

Fast, reliable, and scalable distributed messaging platform.

13971 Stars

Apache Pulsar

Distributed pub/sub-messaging system.

7181 Stars

Aeron

Efficient, reliable, unicast and multicast message transport.

5419 Stars

Apache Camel

Glues together different transport APIs via Enterprise Integration Patterns.

2366 Stars

Smack

Cross-platform XMPP client library.

2345 Stars

JeroMQ

Implementation of ZeroMQ.

2280 Stars

Apache ActiveMQ

Message broker that implements JMS and converts synchronous to asynchronous communication.

1233 Stars

RabbitMQ Java client

RabbitMQ client.

953 Stars

Nakadi

Provides a RESTful API on top of Kafka.

803 Stars

Hermes

Fast and reliable message broker built on top of Kafka.

550 Stars

NATS client

NATS client.

125 Stars

Apache Qpid

Apache Qpid makes messaging tools that speak AMQP and support many languages and platforms.

40 Stars

Deezpatch

Simple, lightweight, and performant dispatch library for decoupling messages (requests and events) and message handlers.

Microservice

Tools for creating and managing microservices.

29526 Stars

Nacos

Dynamic service discovery, configuration and service management platform for building cloud native applications.

22179 Stars

Sentinel

Flow control component enabling reliability, resilience and monitoring for microservices.

13396 Stars

Quarkus

Kubernetes stack tailored for the HotSpot and Graal VM.

12312 Stars

Eureka

REST-based service registry for resilient load balancing and failover.

6005 Stars

Micronaut

Modern full-stack framework with focus on modularity, minimal memory footprint and startup time.

4746 Stars

Armeria

Asynchronous RPC/REST client/server library built on top of Java 8, Netty, HTTP/2, Thrift and gRPC.

4698 Stars

OpenAI-Java

Java libraries for using OpenAI's GPT-3 API.

4222 Stars

JDA

Wrapping of the Discord REST API and its WebSocket events.

3451 Stars

Helidon

Two-style approach for writing microservices: Functional-reactive and as an implementation of MicroProfile.

3352 Stars

kubernetes-client

Client provides access to the full Kubernetes & OpenShift REST APIs via a fluent DSL.

1648 Stars

Apollo

Libraries for writing composable microservices.

846 Stars

ActiveRPC

Lightweight and fast library for complex high-load distributed applications and Memcached-like solutions.

416 Stars

consul-api

Client for the Consul API: a distributed, highly available and datacenter-aware registry/discovery service.

Miscellaneous

Everything else.

88430 Stars

Design Patterns

Implementation and explanation of the most common design patterns.

21007 Stars

FizzBuzz Enterprise Edition

No-nonsense implementation of FizzBuzz made by serious businessmen for serious business purposes. (No explicit license)

16686 Stars

Modern Java - A Guide to Java 8

Popular Java 8 guide.

10645 Stars

OpenRefine

Tool for working with messy data: cleaning, transforming, extending it with web services and linking it to databases.

5989 Stars

J2ObjC

Java-to-Objective-C translator for porting Android libraries to iOS.

5260 Stars

OctoLinker

Browser extension which allows to navigate through code on GitHub more efficiently.

2409 Stars

Jimfs

In-memory file system.

2206 Stars

Svix

Library for the Svix API to send webhooks and verify signatures.

2126 Stars

AWS SDK for Java 2.0

Wrapper around AWS' API.

2040 Stars

LittleProxy

High performance HTTP proxy atop Netty's event-based networking library.

1695 Stars

CQEngine

Ultra-fast, SQL-like queries on Java collections.

1588 Stars

Maven Wrapper

Analogue of Gradle Wrapper for Maven, allows building projects without installing maven.

1449 Stars

jsweet

Source transpiler to TypeScript/JavaScript.

1365 Stars

FF4J

Feature Flags for Java.

1201 Stars

JBot

Framework for building chatbots. (GPL-3.0-only)

1201 Stars

Simple Java Mail

Mailing with a clean and fluent API.

1112 Stars

JBake

Static website generator.

941 Stars

Togglz

Implementation of the Feature Toggles pattern.

879 Stars

Polyglot for Maven

Extensions for Maven 3.3.1+ that allows writing the POM model in dialects other than XML.

652 Stars

Joda-Money

Basic currency and money classes and algorithms not provided by the JDK.

611 Stars

TypeTools

Tools for resolving generic types.

489 Stars

jOOX

Simple wrapper for the org.w3c.dom package, to allow for fluent XML document creation and manipulation with an API inspired by jQuery.

449 Stars

Membrane Service Proxy

Open-source, reverse-proxy framework.

410 Stars

PipelinR

Small utility library for using handlers and commands with pipelines.

392 Stars

Smooks

Framework for fragment-based message processing. (Apache-2.0 OR LGPL-3.0-or-later)

368 Stars

Modernizer

Detect uses of legacy Java APIs.

359 Stars

yGuard

Obfuscation via renaming and shrinking.

224 Stars

JCuda

JCuda offers Java bindings for CUDA and CUDA-related libraries.

157 Stars

MinimalFTP

Lightweight, small and customizable FTP server.

73 Stars

XMLBeam

Processes XML by using annotations or XPath within code.

23 Stars

JObfuscator![c]

Source code obfuscator.

22 Stars

RR4J

RR4J is a tool that records java bytecode execution and later allows developers to replay locally.

Mobile Development

Tools for creating or managing mobile applications.

1672 Stars

Codename One

Cross-platform solution for writing native mobile apps. (GPL-2.0-only WITH Classpath-exception-2.0)

571 Stars

Multi-OS Engine

Open-source, cross-platform engine to develop native mobile (iOS, Android, etc.) apps.

Monitoring

Tools that monitor applications in production.

16846 Stars

zipkin

Distributed tracing system which gathers timing data needed to troubleshoot latency problems in microservice architectures.

13308 Stars

Pinpoint

Open-source APM tool.

7813 Stars

Metrics

Expose metrics via JMX or HTTP and send them to a database.

5353 Stars

hippo4j

Dynamic and observable thread pool framework.

2924 Stars

JavaMelody

Performance monitoring and profiling.

2152 Stars

Prometheus

Provides a multi-dimensional data model, DSL, autonomous server nodes and much more.

1706 Stars

Stagemonitor

Open-source performance monitoring and transaction tracing for JVM apps.

1705 Stars

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.

1220 Stars

Glowroot

Open-source Java APM.

1116 Stars

Sentry ![c]

Integration with [Sentry](https://github.com/getsentry/sentry), an application error tracking and performance analysis platform.

807 Stars

Jolokia

JMX over REST.

573 Stars

Automon

Combines the power of AOP with monitoring and/or logging tools.

555 Stars

Datadog ![c]

Modern monitoring & analytics.

538 Stars

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.

491 Stars

Jaeger client

Jaeger client.

155 Stars

nudge4j

Remote developer console from the browser for Java 8 via bytecode injection.

154 Stars

Sysmon

Lightweight platform monitoring tool for Java VMs.

52 Stars

Failsafe Actuator

Out of the box monitoring of Failsafe Circuit Breaker in Spring-Boot environment.

22 Stars

SPM ![c]

Performance monitor with distributing transaction tracing for JVM apps.

0 Stars

HertzBeat

Real-time monitoring system with custom-monitor and agentless.

Native

For working with platform-specific native libraries.

8385 Stars

JNA

Work with native libraries without writing JNI. Also provides interfaces to common system libraries.

4432 Stars

JavaCPP

Provides efficient and easy access to native C++.

1231 Stars

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](http://openjdk.java.net/projects/panama).

465 Stars

Aparapi

Converts bytecode to OpenCL which allows execution on GPUs.

Natural Language Processing

Libraries that specialize in processing text.

9574 Stars

CoreNLP

Provides a set of fundamental tools for tasks like tagging, named entity recognition, and sentiment analysis. (GPL-3.0-or-later)

471 Stars

CogCompNLP

Provides common annotators for plain text input. (Research and Academic Use License)

194 Stars

DKPro

Collection of reusable NLP tools for linguistic pre-processing, machine learning, lexical resources, etc.

Networking

Libraries for building network servers.

40250 Stars

Dubbo

High-performance RPC framework.

33104 Stars

Netty

Framework for building high-performance network applications.

11288 Stars

gRPC

RPC framework based on protobuf and HTTP/2.

3553 Stars

Undertow

Web server providing both blocking and non-blocking APIs based on NIO. Used as a network layer in WildFly. (LGPL-2.1-only)

2459 Stars

sshj

Programmatically use SSH, SCP or SFTP.

1809 Stars

KryoNet

Provides a clean and simple API for efficient TCP and UDP client/server network communication using NIO and Kryo.

906 Stars

ServiceTalk

Framework built on Netty with APIs tailored to specific protocols and support for multiple programming paradigms.

900 Stars

MINA

Abstract, event-driven async I/O API for network operations over TCP/IP and UDP/IP via Java NIO.

598 Stars

Comsat

Integrates standard Java web-related APIs with Quasar fibers and actors.

241 Stars

Drift

Easy-to-use, annotation-based library for creating Thrift clients and serializable types.

187 Stars

TLS Channel

Implements a ByteChannel interface over SSLEngine, enabling easy-to-use (socket-like) TLS.

154 Stars

Fluency

High throughput data ingestion logger to Fluentd and Fluent Bit.

146 Stars

Grizzly

NIO framework. Used as a network layer in Glassfish.

30 Stars

urnlib

Represent, parse and encode URNs, as in RFC 2141. (GPL-3.0-only)

13 Stars

Commons-networking

Client for server-sent events (SSE).

ORM

APIs that handle the persistence of objects.

19586 Stars

MyBatis

Couples objects with stored procedures or SQL statements.

5833 Stars

Hibernate

Robust and widely used, with an active community. (LGPL-2.1-only)

1449 Stars

Ebean

Provides simple and fast data access.

1270 Stars

ObjectiveSql

ActiveRecord ORM for rapid development and convention over configuration.

436 Stars

SimpleFlatMapper

Simple database and CSV mapper.

428 Stars

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.

399 Stars

Permazen

Language-natural persistence layer.

313 Stars

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.

192 Stars

EclipseLink

Supports a number of persistence standards: JPA, JAXB, JCA and SDO.

PaaS

Java platform as a service.

PDF

Tools to help with PDF files.

3417 Stars

OpenPDF

Open-source iText fork. (LGPL-3.0-only & MPL-2.0)

2543 Stars

Apache PDFBox

Toolbox for creating and manipulating PDFs.

1957 Stars

flyingsaucer

XML/XHTML and CSS 2.1 renderer. (LGPL-2.1-or-later)

1865 Stars

Open HTML to PDF

Properly supports modern PDF standards based on flyingsaucer and Apache PDFBox.

1780 Stars

Tabula

Extracts tables from PDF files.

1587 Stars

iText ![c]

Creates PDF files programmatically.

977 Stars

JasperReports

Complex reporting engine. (LGPL-3.0-only)

428 Stars

Eclipse BIRT

Report engine for creating PDF and other formats (DOCX, XLSX, HTML, etc) using Eclipse-based visual editor.

241 Stars

Dynamic Jasper

Abstraction layer to JasperReports. (LGPL-3.0-only)

200 Stars

DynamicReports

Simplifies JasperReports. (LGPL-3.0-only)

170 Stars

Apache FOP

Creates PDFs from XSL-FO.

Performance analysis

Tools for performance analysis, profiling and benchmarking.

3040 Stars

JITWatch

Analyze the JIT compiler optimisations made by the HotSpot JVM.

2095 Stars

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)

1248 Stars

honest-profiler

Low-overhead, bias-free sampling profiler.

677 Stars

jHiccup

Logs and records platform JVM stalls.

451 Stars

LatencyUtils

Utilities for latency measurement and reporting.

Apache Commons

Reusable, open source Java software.

2686 Stars

Lang

Provides extra functionality for classes in java.lang.

995 Stars

IO

Collection of I/O utilities.

666 Stars

Collections

Extends or augments the Java Collections Framework.

566 Stars

Math

Lightweight, self-contained mathematics and statistics components.

512 Stars

Pool

Generic object pooling component.

453 Stars

Codec

General encoding/decoding algorithms, e.g. phonetic, base64 or URL.

418 Stars

Imaging

Image library.

374 Stars

CSV

Component for reading and writing comma separated value files.

362 Stars

DbUtils

JDBC helper library.

338 Stars

CLI

Command-line arguments parser.

332 Stars

DBCP

Database connection pooling services.

324 Stars

Compress

Defines an API for working with tar, zip and bzip2 files.

278 Stars

BeanUtils

Easy-to-use wrappers around the Java reflection and introspection APIs.

251 Stars

Net

Collection of network utilities and protocol implementations.

239 Stars

BCEL

Byte Code Engineering Library - analyze, create, and manipulate Java class files.

233 Stars

FileUpload

File upload capability for your servlets and web applications.

225 Stars

VFS

Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.

199 Stars

Validator

Framework to define validators and validation rules in an xml file.

193 Stars

Configuration

Reading of configuration/preferences files in various formats.

186 Stars

Jexl

Expression language which extends the Expression Language of the JSTL.

151 Stars

Email

Library for sending e-mail from Java.

142 Stars

Logging

Wrapper around a variety of logging API implementations.

141 Stars

Exec

API for dealing with external process execution and environment management in Java.

95 Stars

Daemon

Alternative invocation mechanism for unix-daemon-like java code.

93 Stars

JCS

Java Caching System.

82 Stars

OGNL

Object-graph navigation language.

71 Stars

Chain

Chain of Responsibility pattern implementation.

53 Stars

Digester

XML-to-Java-object mapping utility.

51 Stars

RNG

Commons Rng provides implementations of pseudo-random numbers generators.

47 Stars

SCXML

Implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine.

45 Stars

RDF

Common implementation of RDF 1.1 that could be implemented by systems on the JVM.

33 Stars

JXPath

Utilities for manipulating Java Beans using the XPath syntax.

29 Stars

Graph

General purpose graph APIs and algorithms.

25 Stars

Proxy

Library for creating dynamic proxies.

24 Stars

BSF

Bean Scripting Framework - interface to scripting languages, including JSR-223.

21 Stars

Functor

Function that can be manipulated as an object, or an object representing a single, generic function.

20 Stars

Weaver

Provides an easy way to enhance (weave) compiled bytecode.

16 Stars

Jelly

XML based scripting and processing engine.

13 Stars

JCI

Java Compiler Interface.

Other

Other kinds of platforms

3613 Stars

Light-4J

Fast, lightweight and productive microservices framework with built-in [security](https://github.com/networknt/light-oauth2/).

1342 Stars

CUBA Platform

High-level framework for developing enterprise applications with a rich web interface, based on Spring, EclipseLink and Vaadin.

239 Stars

Orienteer

Open-source business application platform for rapid configuration/development of CRM, ERP, LMS and other applications.

Processes

Libraries that help the management of operating system processes.

875 Stars

zt-exec

Provides a unified API to Apache Commons Exec and ProcessBuilder.

125 Stars

zt-process-killer

Stops processes started from Java or the system processes via PID.

30 Stars

ch.vorburger.exec

Convenient API around Apache Commons Exec.

Reactive libraries

Libraries for developing reactive applications.

47774 Stars

RxJava

Allows for composing asynchronous and event-based programs using observable sequences.

14200 Stars

vert.x

Polyglot event-driven application framework.

12987 Stars

Akka

Toolkit and runtime for building concurrent, distributed, fault-tolerant and event-driven applications.

4880 Stars

Reactor

Library for building reactive fast-data applications.

4776 Stars

Reactive Streams

Provides a standard for asynchronous stream processing with non-blocking backpressure.

REST Frameworks

Frameworks specifically for creating RESTful services.

9634 Stars

Spark

Sinatra inspired framework.

8480 Stars

Dropwizard

Opinionated framework for setting up modern web applications with Jetty, Jackson, Jersey and Metrics.

3183 Stars

springdoc-openapi

Automates the generation of API documentation using Spring Boot projects.

2467 Stars

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.

1622 Stars

Rapidoid

Simple, secure and extremely fast framework consisting of an embedded HTTP server, GUI components and dependency injection.

1090 Stars

RESTEasy

Fully certified and portable implementation of the JAX-RS specification.

990 Stars

Elide

Opinionated framework for JSON- or GraphQL-APIs based on a JPA data model.

939 Stars

Microserver

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.

937 Stars

RestExpress

Thin wrapper on the JBoss Netty HTTP stack that provides scaling and performance.

680 Stars

Jersey

JAX-RS reference implementation.

645 Stars

Restlet Framework

Pioneering framework with powerful routing and filtering capabilities, and a unified client and server API.

286 Stars

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.

Science

Libraries for scientific computing, analysis and visualization.

3490 Stars

Tablesaw

Includes a data-frame, an embedded column store, and hundreds of methods to transform, summarize, or filter data.

2556 Stars

JGraphT

Graph library that provides mathematical graph-theory objects and algorithms.

1486 Stars

XChart

Light-weight library for plotting data. Many customizable chart types are available.

1174 Stars

JFreeChart

2D chart library for Swing, JavaFX and server-side applications. (LGPL-2.1-only)

663 Stars

JGraphX

Library for visualizing (mainly Swing) and interacting with node-edge graphs.

585 Stars

BioJava

Facilitates processing biological data by providing algorithms, file format parsers, sequencing and 3D visualization commonly used in bioinformatics.

490 Stars

Chart-FX

Scientific charting library with focus on performance optimised real-time data visualisation at 25 Hz update rates for large data sets.

398 Stars

GraphStream

Library for modeling and analyzing dynamic graphs.

238 Stars

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.

129 Stars

LogicNG

Library for creating, manipulating and solving Boolean and Pseudo-Boolean formulas.

127 Stars

Erdos

Modular, light and easy graph framework for theoretic algorithms.

107 Stars

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)

73 Stars

Mines Java Toolkit

Library for geophysical scientific computation, visualization and digital signal analysis.

Search

Engines that index documents for search and analysis.

68663 Stars

Elasticsearch

Distributed, multitenant-capable, full-text search engine with a RESTful web interface and schema-free JSON documents.

2481 Stars

Apache Lucene

High-performance, full-featured, cross-platform, text search engine library.

1100 Stars

Apache Solr

Enterprise search engine optimized for high-volume traffic.

49 Stars

Indexer4j

Simple and light full text indexing and searching library.

Security

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

21173 Stars

Keycloak

Integrated SSO and IDM for browser apps and RESTful web services.

10983 Stars

Cryptomator

Multiplatform, transparent, client-side encryption of files in the cloud. (GPL-3.0-only)

10047 Stars

jjwt

JSON web token for Java and Android.

6167 Stars

DependencyCheck

Detects publicly disclosed vulnerabilities contained within a project's dependencies.

4276 Stars

Apache Shiro

Performs authentication, authorization, cryptography and session management.

2623 Stars

Keywhiz

System for distributing and managing secrets.

2397 Stars

pac4j

Security engine.

2228 Stars

Bouncy Castle

All-purpose cryptographic library and JCA provider offering a wide range of functions, from basic helpers to PGP/SMIME operations.

1828 Stars

Themis

Multi-platform high-level cryptographic library provides easy-to-use encryption for protecting sensitive data: secure messaging with forward secrecy, secure data storage (AES256GCM); suits for building end-to-end encrypted applications.

1028 Stars

Topaz

Fine-grained authorization for applications with support for RBAC, ABAC, and ReBAC.

743 Stars

OpenAM

Access management solution that includes authentication, SSO, authorization, federation, entitlements and web services security.

480 Stars

SSLContext-Kickstart

High-level SSL context builder for configuring HTTP clients with SSL/TLS.

339 Stars

Password4j

User-friendly cryptographic library that supports Argon2, Bcrypt, Scrypt, PBKDF2 and various other cryptographic hash functions.

285 Stars

Nbvcxz

Advanced password strength estimation.

272 Stars

Passay

Enforce password policy by validating candidate passwords against a configurable rule set.

211 Stars

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.

208 Stars

Kalium

Binding for the Networking and Cryptography (NaCl) library.

193 Stars

Jwks RSA

JSON Web Key Set parser.

175 Stars

OTP-Java

One-time password generator library according to RFC 4226 (HOTP) and RFC 6238 (TOTP).

105 Stars

OACC

Provides permission-based authorization services.

44 Stars

SecurityBuilder

Fluent Builder API for JCA and JSSE classes and especially X.509 certificates.

10 Stars

jwt-java

Easily create and parse JSON Web Tokens and create customized JWT validators using a fluent API.

0 Stars

Tink

Provides a simple and misuse-proof API for common cryptographic tasks.

Serialization

Libraries that handle serialization with high efficiency.

22590 Stars

FlatBuffers

Memory-efficient serialization library that can access serialized data without unpacking and parsing it.

6132 Stars

Kryo

Fast and efficient object graph serialization framework.

1579 Stars

FST

JDK-compatible, high-performance object graph serialization.

1398 Stars

MessagePack

Efficient binary serialization format.

15 Stars

PHP Serializer

Serializing objects in the PHP serialization format.

0 Stars

Fury

A blazing fast multi-language serialization framework powered by jit and zero-copy.

Server

Servers specifically used to deploy applications.

7387 Stars

Apache Tomcat

Robust, all-round server for Servlet and JSP.

6894 Stars

nanohttpd

Tiny, easily embeddable HTTP server.

3795 Stars

Jetty

Provides a Web server and javax.servlet container, plus support for HTTP/2, WebSocket, OSGi, JMX, JNDI, JAAS and many other integrations.

3022 Stars

WildFly

Formerly known as JBoss and developed by Red Hat with extensive Java EE support. (LGPL-2.1-only)

447 Stars

Apache TomEE

Tomcat plus Java EE.

Template Engine

Tools that substitute expressions in a template.

2761 Stars

Thymeleaf

Aims to be a substitute for JSP and works for XML files.

1441 Stars

Handlebars.java

Logicless and semantic Mustache templates.

1078 Stars

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.

949 Stars

Freemarker

Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.

939 Stars

StringTemplate

Template engine for generating source code, web pages, emails, or any other formatted text output.

737 Stars

jte

Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.

734 Stars

Rocker

Optimized, memory efficient and speedy template engine producing statically typed, plain objects.

704 Stars

Jade4J

Implementation of Pug (formerly known as Jade).

300 Stars

Jtwig

Modular, configurable and fully tested template engine.

238 Stars

jstachio

Typesafe Mustache templating engine.

57 Stars

Jamal

Extendable template engine embedded into Maven/JavaDoc, supporting multiple extensions (Groovy, Ruby, JavaScript, JShell, PlantUml) with support for snippet handling.

Testing

Tools that test from model to the view.

BDD

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

2687 Stars

Cucumber

Provides a way to describe features in a plain language which customers can understand.

715 Stars

Serenity BDD

Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.

433 Stars

JGiven

Provides a fluent API which allows for simpler composition.

253 Stars

Lamdba Behave

Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.

158 Stars

JBehave

Extensively configurable framework that describes stories.

107 Stars

Cukes-REST

Collection of Gherkin steps for REST-service testing using Cucumber.

46 Stars

J8Spec

Follows a Jasmine-like syntax.

Fixtures

Everything related to the creation and handling of random data.

4647 Stars

Java Faker

Port of Ruby's fake data generator.

831 Stars

Instancio

Automates data setup in unit tests by generating fully-populated, reproducible objects. Includes JUnit 5 extension.

738 Stars

jFairy

Fake data generator.

525 Stars

Mockneat

Another fake data generator.

443 Stars

Fixture Factory

Generates fake objects from a template.

172 Stars

Randomized Testing

JUnit test runner and plugins for running JUnit tests with pseudo-randomness.

113 Stars

Beanmother

Sets up beans from YAML fixtures.

Frameworks

Provide environments to run tests for a specific use case.

8114 Stars

Apache JMeter

Functional testing and performance measurements.

6339 Stars

Gatling

Load testing tool designed for ease of use, maintainability and high performance.

6240 Stars

JUnit

Common testing framework.

3126 Stars

ArchUnit

Test library for specifying and asserting architecture rules.

1658 Stars

PIT

Fast mutation-testing framework for evaluating fault-detection abilities of existing JUnit or TestNG test suites.

1066 Stars

Pact JVM

Consumer-driven contract testing.

553 Stars

jqwik

Engine for property-based testing built on JUnit 5.

450 Stars

Citrus

Integration testing framework that focuses on both client- and server-side messaging.

369 Stars

Arquillian

Integration and functional testing platform for Java EE containers.

Matchers

Libraries that provide custom matchers.

2710 Stars

Truth

Google's fluent assertion and proposition framework.

2585 Stars

AssertJ

Fluent assertions that improve readability.

2094 Stars

Hamcrest

Matchers that can be combined to create flexible expressions of intent.

977 Stars

JSONAssert

Simplifies testing JSON strings.

871 Stars

JsonUnit

Library that simplifies JSON comparison in tests.

291 Stars

XMLUnit

Simplifies testing for XML output.

Miscellaneous

Other stuff related to testing.

7899 Stars

TestContainers

Provides throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container.

348 Stars

LogCaptor

Captures log entries for unit testing purposes.

243 Stars

junit-dataprovider

TestNG-like data provider/runner for JUnit.

239 Stars

Mutability Detector

Reports whether instances of a given class are immutable.

71 Stars

raml-tester

Tests if a request/response matches a given RAML definition.

52 Stars

pojo-tester

Automatically performs tests on basic POJO methods. (LGPL-3.0-only)

29 Stars

ConsoleCaptor

Captures console output for unit testing purposes.

12 Stars

log-capture

Captures log entries and provides assertions for unit and integration testing.

Mocking

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

14716 Stars

Mockito

Mocking framework that lets you write tests with a clean and simple API.

6198 Stars

WireMock

Stubs and mocks web services.

4527 Stars

MockServer

Allows mocking of systems integrated with HTTPS.

4337 Stars

Moco

Concise web services for stubs and mocks.

4139 Stars

PowerMock

Mocks static methods, constructors, final classes and methods, private methods, and removal of static initializers.

458 Stars

JMockit

Integration testing, API mocking and faking, and code coverage.

Utility

Libraries which provide general utility functions.

49713 Stars

Guava

Collections, caching, primitives support, concurrency libraries, common annotations, string processing, I/O, and more.

35115 Stars

Arthas

Allows to troubleshoot production issues for applications without modifying code or restarting servers.

5758 Stars

Gephi

Cross-platform for visualizing and manipulating large graph networks. (GPL-3.0-only)

2617 Stars

JavaVerbalExpressions

Library that helps with constructing difficult regular expressions.

2231 Stars

bucket4j

Rate limiting library based on token-bucket algorithm.

1739 Stars

Embulk

Bulk data loader that helps data transfer between various databases, storages, file formats, and cloud services.

1318 Stars

Dex

Java/JavaFX tool capable of powerful ETL and data visualization.

1235 Stars

Java Diff Utils

Utilities for text or data comparison and patching.

1068 Stars

minio-java

Provides simple APIs to access any Amazon S3-compatible object storage server.

973 Stars

Protégé

Provides an ontology editor and a framework to build knowledge-based systems.

929 Stars

CRaSH

Provides a shell into a JVM that's running CRaSH. Used by Spring Boot and others. (LGPL-2.1-or-later)

734 Stars

cactoos

Collection of object-oriented primitives.

524 Stars

Underscore-java

Port of Underscore.js functions.

42 Stars

JGit

Lightweight, pure Java library implementing the Git version control system.

38 Stars

Chocotea

Generates postman collection, environment and integration tests from java code.

28 Stars

fswatch

Micro library to watch for directory file system changes, simplifying java.nio.file.WatchService.

Version Managers

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

5988 Stars

SDKMan

Java Version Manager inspired by RVM and rbenv. Supports UNIX-based platforms.

5631 Stars

jenv

Java Version Manager inspired by rbenv. Can configure globally or per project. Tested on Debian and macOS.

2938 Stars

jabba

Java Version Manager inspired by nvm. Supports macOS, Linux and Windows.

Web Crawling

Libraries that analyze the content of websites.

11331 Stars

webmagic

Scalable crawler with downloading, url management, content extraction and persistent.

10798 Stars

jsoup

Scrapes, parses, manipulates and cleans HTML.

4513 Stars

Crawler4j

Simple and lightweight web crawler.

2855 Stars

Apache Nutch

Highly extensible, highly scalable web crawler for production environments.

0 Stars

StormCrawler

SDK for building low-latency and scalable web crawlers.

Web Frameworks

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

12521 Stars

Play

Built on Akka, it provides predictable and minimal resource consumption (CPU, memory, threads) for highly-scalable applications in Java and Scala.

7396 Stars

Javalin

Microframework for web applications.

5829 Stars

Blade

Lightweight, modular framework that aims to be elegant and simple.

1936 Stars

Ratpack

Set of libraries that facilitate fast, efficient, evolvable and well-tested HTTP applications.

1908 Stars

Ninja

Full-stack web framework.

1774 Stars

Vaadin

Event-driven framework that uses standard web components. Server-side architecture with Ajax on the client side.

1765 Stars

PrimeFaces

JSF framework with both free and commercial/support versions and frontend components.

1681 Stars

Jooby

Scalable, fast and modular micro-framework that offers multiple programming models.

1416 Stars

Bootique

Minimally opinionated framework for runnable apps.

846 Stars

ActiveJ

Lightweight asynchronous framework built from the ground up for developing high-performance web applications.

801 Stars

Takes

Opinionated web framework which is built around the concepts of True Object-Oriented Programming and immutability.

786 Stars

Pippo

Small, highly modularized, Sinatra-like framework.

724 Stars

Apache Wicket

Component-based web application framework similar to Tapestry, with a stateful GUI.

296 Stars

Firefly

Asynchronous framework for rapid development of high-performance web application.

118 Stars

Apache Tapestry

Component-oriented framework for creating dynamic, robust, highly scalable web applications.

About

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