Front End (Frameworks and Libraries) : AngularJS , React.js , jQuery, SASS , Flutter, and some other libraries and frameworks
Back End Frameworks: Express, Django, Rails, Laravel, Spring, etc.
If u wants to became an backend developer
Then u must need a basic knwoldege of these - html,css,js
So that u can work easily on backend
Bcz backend is nothing without frontend
Some common backend languages are Ruby, PHP, Java, .Net, and Python. These programming languages often run on frameworks that simplify the web development process.
Majority of websites on the world wide web use PHP as the backend. The language will top any list of popular programming languages. The language is maintained by a very active open source community and can seamlessly work cross-platform across UNIX, Mac and Windows.