Varnish

Varnish Cache is a web application accelerator also referred to as a caching HTTP reverse proxy. You can install it in front of any server that speaks the HTTP protocol and configure it to cache the content. Varnish Cache is really, really fast and will improve your website's speed. One of the important virtues of Varnish Cache is the flexibility of its domain-specific language, VCL, which enables you to specify how incoming requests should be handled.

Memcached

Memcached is a general-purpose distributed memory object caching system for increasing the load speed of dynamic database-powered web sites. It is used to lower the number of times an external data source (such as a DB or API) is read by caching data and objects in RAM. The Memcached distributed memory object caching system uses a client'server architecture. The Memcached system is used by some of the most regularly visited sites on the web and is supported by popular web apps like Joomla and WordPress.

Node.js

Node.js is a software system for building scalable network apps. Built on Chrome's JavaScript runtime, Node.js uses an event-based, non-blocking input/output model that makes it lightweight and efficient, suitable for real-time content-rich applications. Node.js uses Google's V8 JavaScript engine, libUV, and a number of built-in libraries.

InnoDB

InnoDB is the default storage engine for the MySQL open-source relational database management system. A database engine is the primary software component that a database management system uses to create, retrieve, modify and delete data from a database. Its latest edition offers substantial improvements in performance, reliability and usability. InnoDB provides the standard ACID transaction features, as well as referential integrity support. It is included as standard in most binary distributions from MySQL AB.