A realtime distributed messaging platform

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

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

The most scalable and reliable MQTT broker for AI, IoT, IIoT and connected vehicles

IM Chat ChatGPT OpenClaw

Apache Pulsar - distributed pub-sub messaging system

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

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

An elegant messages UI library for iOS

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

SimpleX - the first messaging network operating without user identifiers of any kind - 100% private by design! iOS, Android and desktop apps 📱!

Scalable real-time messaging server in a language-agnostic way. Self-hosted alternative to Pubnub, Pusher, Ably, socket.io, Phoenix.PubSub, SignalR. Set up once and forever.

Berty is a secure peer-to-peer messaging app that works with or without internet access, cellular data or trust in the network

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

Distributed Application Framework for .NET

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

A community-driven replacement for JSQMessagesViewController

Apache Kafka® running on Kubernetes

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

qTox is a chat, voice, video, and file transfer IM client using the encrypted peer-to-peer Tox protocol.

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

Orchestrate end-to-end encryption, cryptographic identities, mutual authentication, and authorization policies between distributed applications – at massive scale.

The most widely used PHP client for RabbitMQ

The most beautiful SMS messenger for Android

⚡️ A framework for building conversational user interfaces.

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

Anonymous peer-to-peer instant messaging

Apache Iggy: Hyper-Efficient Message Streaming at Laser Speed

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

A dead simple Go library for sending notifications to various messaging services.