Pusher!

GUN is an open source, realtime, graph database written entirely in JavaScript and built using peer-to-peer algorithms, making it surprisingly fault tolerant and easy to get started with.

PubNub is the world’s only global Real-Time Network. PubNub enables software developers to rapidly build and scale real-time apps by providing the cloud infrastructure, connections and key building blocks for real-time interactivity. Developers can build real-time apps like live dashboards and data streams, real-time collaboration, 2nd screen synchronization and machine-to-machine signaling for any device. PubNub utilizes a Publish/Subscribe model for real-time data streaming and device signaling and supports all of the capabilities of WebSockets, Socket.IO, SignalIR, WebRTC Data Channel and other streaming protocols. With PubNub, developers can dramatically reduce the cost, complexity and time to deliver real-time experiences. »

Emitter is a real-time communication service for connecting online devices. Infrastructure and APIs for IoT, gaming, apps and real-time web. At its core, emitter.io is a distributed, scalable and fault-tolerant publish-subscribe messaging platform based on MQTT protocol and featuring message storage.

ScaleDrone is a push messaging service focusing on security.

JBoss is Red Hats Java EE 5-compliant (soon Java EE 6-compliant) application server. It is, as with Red Hat itself, dual-licensed either as open source (community edition) or commercially (enterprise edition).

Rapid.io is a cloud-hosted service that allows app developers to build realtime user interfaces without having to worry about the underlying infrastructure. It works as a non-relational data store accessible from client-side code. Clients can subscribe to a set of data and receive updates in realtime.

A secure realtime server, supporting data-sync, RPCs and events

MongooseIM is aimed at large, complex enterprise level projects, where real-time communication is critical for business success. It provides high availability, ease of deployment, development and reliability in production.

Bone.io allows you to build realtime JavaScript apps using WebSockets to deliver "hot" data to the browser. This enables you to easily construct rich, highly responsive user interfaces.

Socket.IO aims to make real-time apps possible in every browser and mobile device, blurring the differences between the different transport mechanisms. It's care-free open source real-time 100% in JavaScript.

Simperium is a service for developers to move data everywhere it's needed, instantly and automatically.

Lightstreamer is a server for delivering real-time messages to browser-based and mobile applications, using WebSockets and HTTP. Features include dynamic throttling, bandwidth and frequency control, delta delivery, and total control over security and the quality of service.

The Jetty Web Server provides a HTTP server and Servlet container capable of serving static and dynamic contend either from a standalone or embedded instantiations.