Varnish

Varnish Cache is a web accelerator also popular 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 site's loading speed. One of the chief virtues of Varnish Cache is the flexibility of its domain-specific language, VCL, which permits you to determine how incoming requests should be tackled.

Memcached

Memcached is a generic distributed memory caching system for boosting the loading 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 object caching system is used by some of the most regularly visited websites on the Internet and is supported by famous CMSs like Joomla and WordPress.

Node.js

Node.js is a software platform for writing scalable Internet apps. Built on Chrome's JavaScript runtime, Node.js uses an event-based, asynchronous I/O model that makes it lightweight and efficient, suitable for real-time data-rich applications. Node.js uses Google's V8 JavaScript engine, libUV, and several built-in libraries.

InnoDB

InnoDB is the default database engine for the MySQL open-source RDBMS. A database engine is the main software component that a database management system uses to create, retrieve, modify and delete data from a database. Its latest release features considerable improvements in efficacy, stability and usability. InnoDB offers the standard ACID-compliant transaction features, along with declarative referential integrity support. InnoDB is included by default in most binary distributions from MySQL AB.