htmlreference.io - Learn by example with this free web-based guide to HTML.
W3Schools - W3Schools is a web developers information website, with tutorials and references on web development...
Web4College - Web4College is a unique website that includes the web development tutorials and takes the design of a website to the next level. In this website, every topic is dealt with the basic concepts, detailed study, examples, and implementations.
CSS Reference - Sleek and comprehensive online reference for CSS
MarkSheet - Browser-based guide and tutorial for HTML and CSS tutorial
Reactgo - It provides tutorials about, JavaScript, react.js , Vue js , angular etc