Emitter.io is a real-time messaging service for connecting online devices. - scalable: Built to handle millions of messages per second and to scale horizontally. - Fast: Designed to ensure reliable, speed-of-light message delivery and high throughput. - Secure: Supports TLS encryption, binary messages, expirable channel keys and permissions. - Open source: Source code is available on GitHub and packaged as a docker container. - Persistant: Messages can be stored for a period of time and sent to subscribers on demand. - No more limits: Uses standard MQTT protocol, supports message filtering.