Varnish

Varnish Cache is a web accelerator also known as a caching HTTP reverse proxy. You can install it in front of any web server that speaks the HTTP protocol and configure it to cache the content. Varnish Cache is really, really fast and will improve your site's loading speed. One of the essential pluses of Varnish Cache is the flexibility of its principal configuration mechanism, VCL, which enables you to specify how incoming requests should be tackled.

Memcached

Memcached is a generic memory object caching system for increasing the loading speed of dynamic database-driven web sites. It is used to reduce 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 memory caching system uses a client/server architecture. The Memcached system is employed by some of the most traffic-heavy sites on the web and is supported by popular web applications like Joomla and WordPress.

Node.js

Node.js is a software platform for building scalable Internet applications. Built on Chrome's JavaScript runtime, Node.js uses an event-driven, non-blocking input/output model that makes it lightweight and effective, excellent for high-performance content-heavy Internet applications. Node.js uses Google's V8 JavaScript engine, libUV, and several built-in libraries.

InnoDB

InnoDB is the default storage engine for the MySQL open-source DBMS. A storage engine is the primary software component that a DBMS uses to create, read, modify and delete data from a database. The latest edition of InnoDB features serious improvements in performance, dependability and usability. InnoDB offers the standard ACID database transaction properties, along with referential integrity support. InnoDB is included by default in most binary distributions from MySQL AB.