Emitter: Scalable Real-Time Communication Across Devices

Emitter.io is a high-performance, distributed publish-subscribe platform using the MQTT protocol for scalable real-time communication between online devices.

🚀 Overview

Emitter solves the problem of implementing reliable, low-latency real-time messaging in applications like online games, IoT systems, live dashboards, and mobile apps, where traditional polling or WebSockets fall short in scalability and performance.

It's built for developers and teams who need a robust backend for pub-sub messaging without managing infrastructure.

The project was created to provide a fault-tolerant, high-throughput service (over 3 million messages per second per broker) that's easy to integrate via standard MQTT, with options for cloud hosting or self-hosting the open-source version.

✨ Key Features

Scalable to millions of messages per second with horizontal scaling and fault-tolerance
Ultra-low latency delivery with high throughput and binary message support
Secure communication via TLS encryption, expirable channel keys, and permission controls
Persistent message storage to deliver messages to late-joining subscribers
Standard MQTT over TCP/WebSockets, compatible with any MQTT client library
Upcoming or experimental: Enhanced monitoring integrations

🛠 Tech Stack

Backend: Go (primary language), MQTT protocol
Deployment: Docker, Kubernetes
Monitoring: Prometheus, StatsD
Security: TLS/SSL, encrypted inter-broker comms
Clients: JavaScript (npm: emitter-io), Python (PyPI: emitter-io), and more
Database: Built-in message storage
Auth: Custom channel/secret keys
Hosting: Self-hosted or Vercel-like cloud (emitter.io hosted)

👥 Who Is This For?

This project is useful for:

Developers who want to add real-time features to web and mobile apps
IoT teams connecting and controlling thousands of devices
Game developers building multiplayer experiences with low latency
Teams looking for live data visualization and collaborative tools

📸 Screenshots / Demo

Live demo: https://emitter.io (sign up for free cloud trial)
GitHub: https://github.com/emitter-io/emitter

🔥 Project Status

🟡 Maintained

Last updated: 2024-02-02

❓ FAQ

Is this project free?

Freemium - Generous free tier in cloud (e.g., ~1GB storage, 15GB data transfer, 500 unique devices monthly), then metered billing ($1 per extra GB transfer, $0.10 per extra device). Open source self-hosting is completely free under AGPL.