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

Hystrix is a latency and fault tolerance library designed to isolate points of access to remote systems, services and 3rd party libraries, stop cascading failure and enable resilience in complex di…

Zipkin is a distributed tracing system

Modern Java - A Guide to Java 8

🏗 Build container images for your Java applications.

Style and Grammar Checker for 25+ Languages

OpenRefine is a free, open source power tool for working with messy data and improving it

A collection of source code generators for Java.

Resilience4j is a fault tolerance library designed for Java8 and functional programming

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

GoCD - Continuous Delivery server main repository

An application observability facade for the most popular observability tools. Think SLF4J, but for observability.

Ribbon is a Inter Process Communication (remote procedure calls) library with built in software load balancers. The primary usage model involves REST calls with various serialization scheme support.

Azkaban workflow manager.

Open Location Code is a library to generate short codes, called "plus codes", that can be used as digital addresses where street addresses don't exist.

Java annotation processor to create immutable objects and builders, for records too. Sweep boilerplate code under the rug!

Apache Avro is a data serialization system.

Implementation of various string similarity and distance algorithms: Levenshtein, Jaro-winkler, n-Gram, Q-Gram, Jaccard index, Longest Common Subsequence edit distance, cosine similarity ...

Java regular expressions made easy.

https://openjdk.org/projects/code-tools/jmh

Library for configuration management API

FitNesse -- The Acceptance Test Wiki

Lean & powerful HTTP apps

Concise UI Tests with Java!

Broadleaf Commerce CE - an eCommerce framework based on Java and Spring

Feature Flags for Java made easy

Advanced manager and monitor for Apache Tomcat, forked from Lambda Probe

Simple Java image-scaling library implementing Chris Campbell's incremental scaling algorithm as well as Java2D's "best-practices" image-scaling techniques.

Work in progress transmit from Google Code

Nginx module for embedding Clojure or Java or Groovy programs, typically those Ring based handlers.