this website ;)
webplatform.org W3C documentation
mva.microsoft.com Microsoft Virtual Academy
w3schools.com
youtube-channel with many tutorials
notepad++ Editor
codepen.io try out HTML, CSS and Javascript code online
caniuse.com look up browser-support
html validator
bootstrap Framework for responsive webdesign
jquery JavaScript library
threejs 3D library
this website ;)
zagler-art.at (german)