Externalized Propertiesstars14 - Lightweight but powerful configuration library which supports resolution of properties from external sources and an extensible post-processing/conversion mechanism.
Date and Time
Jollydaystars170 - Determines the holidays for a given year, country/name and eventually state/region.
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.
RR4Jstars13 - RR4J is a tool that records java bytecode execution and later allows developers to replay locally.
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.
jwt-javastars7 - Easily create and parse JSON Web Tokens and create customized JWT validators using a fluent API.
Nov 8th, 2021
Groundbreakers - Oracle ACEs, Groundbreaker Ambassadors and Java Champions.
jtestars394 - Compiles to classes, and uses an easy syntax, several features to make development easier and provides fast execution and a small footprint.
ActiveJ - Lightweight asynchronous framework built from the ground up for developing high-performance web applications.
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.
Telosys - Simple and light code generator available as an Eclipse Plugin and also as a CLI.
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.
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 23rd, 2020
Mini2Dx - Beginner-friendly, master-ready framework for rapidly prototyping and building 2D games.
Debezium - Low latency data streaming platform for change data capture.
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.
configstars5.7k - Configuration library supporting Java properties, JSON or its human optimized superset HOCON.
May 9th, 2020
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 23rd, 2020
Eclipse BIRT - Report engine for creating PDF and other formats (DOCX, XLSX, HTML, etc) using Eclipse-based visual editor.
Apr 22nd, 2020
Freemarker - Library to generate text output (HTML web pages, e-mails, configuration files, source code, etc.) based on templates and changing data.
Apr 7th, 2020
hatestars20 - Builds hypermedia-friendly objects according to HAL specification.
Apr 3rd, 2020
JVM and JDK
Dragonwell8stars3.6k - Downstream version of OpenJDK optimized for online e-commerce, financial, logistics applications.
Mar 25th, 2020
Sentinelstars19.3k - Flow control component enabling reliability, resilience and monitoring for microservices.
Arthasstars29.5k - Allows to troubleshoot production issues for applications without modifying code or restarting servers.
Tail - Enable infinite recursion using tail call optimization.
Mar 14th, 2020
Cloudsmith - Fully managed package management SaaS with support for Maven/Gradle/SBT with a free tier.
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.
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)
H2GIS - Spatial extension of the H2 database. (LGPL-3.0-only)