Less which stands for Leaner Style Sheets is a backwards-compatible language extension for CSS. This is the official documentation for Less, the language and Less.js, the JavaScript tool that converts your Less styles to CSS styles.
PHP: Hypertext Preprocessor is a server-side scripting language designed for Web development, but also used as a general-purpose programming language. PHP code may be embedded into HTML code, or it can be used in combination with various web template systems, web content management systems, and web frameworks.
Mailchimp Transactional Email (formerly Mandrill) is a reliable, scalable and secure delivery API for transactional emails from websites and applications.