PHP7
Prefer OOP. Web Framework (Slim, Laravel), ORM (Propel, Eloquent).
JavaScript
Node.js (Multi-platform resource monitoring), ES2015.
Frontend
React.js (Admin tool), Angular.js (1.x) (SP), Sass, Slim.
MySQL
DB Designing.
Linux Server
Ubuntu, CentOS, Httpd (Apache2, Nginx), DNS (BIND), Postfix, Dovecot (Beginner), VPN (OpenVPN, L2TP over IPsec).
Others
C, C++, Scala, Java (Android), Python, Haskell (Beginner).