Socket.io - Realtime application framework (Node.JS server)
Docker - Docker is an open platform that enables developers and system administrators to create distributed applications.
Ably - Serious realtime infrastructure
Kubernetes - Kubernetes is an open source orchestration system for Docker containers
Pusher - Pusher is a hosted API for quickly, easily and securely adding scalable realtime functionality via WebSockets to web and mobile apps.
Amazon ECS - Amazon EC2 Container Service is a highly scalable, high-performance container management service that supports Docker containers.