Varnish - High-performance HTTP accelerator
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
Section - gosection8.
memcached - High-performance, distributed memory object caching system
nginx - A high performance free open source web server powering busiest sites on the Internet.
MongoDB - MongoDB (from "humongous") is a scalable, high-performance NoSQL database.