Server scripting 

  1. PHP

UI/UX

  1. CSS 1, CSS 2, CSS 3 (pre-processors: SASS, SCSS)

Databases

  1. PHPmyAdmin
  2. MySQL

OS

  1. SSH: Linux distro’s (Ubuntu, CentOS 6, CentOS 7)
  2. MacOS
  3. Windows

Software optimalisation

  1. PHP 5 / PHP 7
  2. MariaDB / Percona