System design 

Tushar Roy

System Design Introduction For Interview.

Youtube system design 

Language specific questions, concurrency , parallellism

Framework

Backend: django, spring,

FrontEnd: react, vue

redis, celery: asynchronous task queue

Introduction to the DOM 

Resources

system-design-primer 

Grokking the System Design Interview 

Designing Data-Intensive Applications: The Big Ideas Behind Reliable, Scalable, and Maintainable Systems 

Latency Numbers Every Programmer Should Know