Socket.io - Realtime application framework (Node.JS server)
Ansible - Radically simple configuration-management, application deployment, task-execution, and multi-node orchestration engine
Ably - Serious realtime infrastructure
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.
Puppet Enterprise - Get started with Puppet Enterprise, or upgrade or expand.