Frontend
HTML
CSS
JavaScript / TypeScript
React
AngularJS
Vue.js
GWT
Mobile
Android (Java)
iOS (Objective C, Swift)
React Native
Databases
PostgreSQL
Oracle
Cassandra
Elastic Search
Redis
MongoDB
CouchDB
API development
REST
JSON
OAuth
JWT
Webhooks
WebSockets
SOAP
Middleware and cloud technologies
Open-Source
Docker
Kubernetes
HW virtualisation
Hadoop
Cloudera
Apache Spark
Impala
etc.
Applications
Java
C/C++
Node.js
Data management and computerized learning
C/C++
C#
Python
CNN
TensorFlow