Apache RocketMQ is a cloud native messaging and streaming platform, making it simple to build event-driven applications.

Apache Pulsar - distributed pub-sub messaging system

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

Apache Kafka® running on Kubernetes

signal-cli provides an unofficial commandline, JSON-RPC and dbus interface for the Signal messenger.

Android library. Flexible components for chat UI implementation with flexible possibilities for styling, customizing and data management. Made by Stfalcon

Apache Heron (Incubating) is a realtime, distributed, fault-tolerant stream processing engine from Twitter

JeroMQ is a pure Java implementation of the ZeroMQ messaging library, offering high-performance asynchronous messaging for distributed or concurrent applications.

Apache ActiveMQ

RocketMQ企业级一站式服务平台

Chat SDK Android - Open Source Mobile Messenger

HiveMQ CE is a Java-based open source MQTT broker that fully supports MQTT 3.x and MQTT 5. It is the foundation of the HiveMQ Enterprise Connectivity and Messaging Platform

Framework for building Event-Driven Microservices

Apache ActiveMQ Artemis

Threema App for Android.

Fast and reliable message broker built on top of Kafka.

Countly Product Analytics Android SDK

Java client for NATS

Eclipse Hono™ Project

Framework for automated integration tests with focus on message-based applications