Java

Jetty, Spring Boot, Spring4-* (core,data,security, ...)

JavaScript

AngularJS, NodeJS, Gulp, Grunt, Express, Mongoose, Passport, C++/V8 native Addons

Database

SQL, NoSQL(MongoDB)

Misc

Bash, Python, Git, Go

Administration

Linux, Docker, AWS (EC2, ECR, Cloudwatch etc.), scalability, high availability, Monitoring, Continuous integration (Jenkins)