Varnish

Varnish Cache is a web accelerator also popular as a caching HTTP reverse proxy. You can install it in front of any web server that speaks HTTP and configure it to cache the content. Varnish Cache is really, really fast and will speed up your web site. One of the chief strengths of Varnish Cache is the flexibility of its principal configuration mechanism, VCL, which permits you to choose how incoming requests should be handled.

Memcached

Memcached is a generic memory object caching system for boosting the speed of dynamic database-driven web sites. It is used to decrease 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 system uses a client/server architecture. The Memcached memory caching system is used by some of the most traffic-intensive sites on the web and is supported by popular web apps like Joomla and WordPress.

Node.js

Node.js is a software system for writing scalable Internet applications. Written in JavaScript, Node.js uses an event-driven, non-blocking input/output model that makes it lightweight and effective, ideal for real-time content-heavy apps. Node.js uses Google's V8 JavaScript engine, libUV, and a number of built-in libraries.

InnoDB

InnoDB is the default database engine for the MySQL open-source database management system. A storage engine is the main software component that a DBMS uses to create, retrieve, modify and delete data from a database. The latest release of InnoDB features considerable improvements in efficacy, reliability and functionality. InnoDB provides the standard ACID-compliant database transaction features, as well as foreign key support. InnoDB is included by default in most binaries distributed by MySQL AB.