A realtime distributed messaging platform

An elegant messages UI library for iOS

High-Performance server for NATS, the cloud native messaging system.

Open source RabbitMQ: core server and tier 1 (built-in) plugins

EMQ X Broker - Scalable Distributed MQTT Message Broker for IoT in 5G Era

Apache Pulsar - distributed pub-sub messaging system

ZeroMQ core engine in C++, implements ZMTP/3.1

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

Instant messaging platform. Backend in Go. Clients: Swift iOS, Java Android, JS webapp, scriptable command line; chatbots

Scalable real-time messaging server in language-agnostic way

Robust, Ubiquitous and Massively Scalable Messaging Platform (XMPP, MQTT, SIP Server)

A community-driven replacement for JSQMessagesViewController

Kafka implemented in Golang with built-in coordination (No ZK dep, single binary install, Cloud Native)

Open source, native iOS Messenger, with audio/video calls and realtime chat conversations (full offline support).

Franz is a free messaging app for services like WhatsApp, Slack, Messenger and many more.

The most widely used PHP client for RabbitMQ

⚡️ A framework for building conversational user interfaces.

Anonymous peer-to-peer instant messaging

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

Distributed Application Framework for .NET

The most beautiful SMS messenger for Android

ChatSecure is a free and open source encrypted chat client for iOS that supports OTR and OMEMO encryption over XMPP.

Private messaging system that hides metadata

A 100% native C# implementation of ZeroMQ for .NET

Apache Kafka running on Kubernetes

Messaging library for Python.

Lightweight, fault-tolerant message streams.

Crossbar.io - WAMP application router