Ghidra is a software reverse engineering (SRE) framework

RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.

a fast, scalable, multi-language and extensible build system

Open-source IoT Platform - Device management, data collection, processing and visualization.

光 HikariCP・A solid, high-performance, JDBC connection pool at last.

A high performance caching library for Java

Zipkin is a distributed tracing system

Apache Pulsar - distributed pub-sub messaging system

Suite of tools for deploying and training deep learning models using the JVM. Highlights include model import for keras, tensorflow, and onnx/pytorch, a modular and tiny c++ library for running mat…

Apache Druid: a high performance real-time analytics database.

Java JsonPath implementation

Efficient reliable UDP unicast, UDP multicast, and IPC message transport

📈 Capturing JVM- and application-level metrics. So you know what's going on.

Runtime code generation for the Java virtual machine.

Haven is for people who need a way to protect their personal spaces and possessions without compromising their own privacy, through an Android app and on-device sensors

Open source routing engine for OpenStreetMap. Use it as Java library or standalone web server.

Generate Java types from JSON or JSON Schema and annotate those types for data-binding with Jackson, Gson, etc

Statistical Machine Intelligence & Learning Engine

configuration library for JVM languages using HOCON files

Drools is a rule engine, DMN engine and complex event processing (CEP) engine for Java

Distributed Graph Database

MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap-memory. It is a fast and easy to use embedded Java database engine.

Speech and Vision Based Intelligent Personal Assistant

Azkaban workflow manager.

Jitsi is an audio/video and chat communicator that supports protocols such as SIP, XMPP/Jabber, IRC and many other useful features.

Fault tolerance and resilience patterns for the JVM

Real-time transport layer for Java AI agents. Build once with @Agent — deliver over WebSocket, SSE, gRPC, and WebTransport/HTTP3. Talk MCP, A2A and AG-UI.

Source-agnostic distributed change data capture system

Generates a unified GraphQL schema from gRPC microservices and other Protobuf sources

Unirest in Java: Simplified, lightweight HTTP client library.