Varnish is a reverse caching proxy.

PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.

Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.

WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system.

MySQL is an open-source relational database management system.

Contact Form 7 is an WordPress plugin which can manage multiple contact forms. The form supports Ajax-powered submitting, CAPTCHA, Akismet spam filtering.

reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.

jQuery is a JavaScript library which is a free, open-source software designed to simplify HTML DOM tree traversal and manipulation, as well as event handling, CSS animation, and Ajax.

Google Analytics is a free web analytics service that tracks and reports website traffic.

PHP is a general-purpose scripting language used for web development.

Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.