Im coding webapp where user has ability to enter web-addr and script will enter desired webpage.

When coding in WinForms, OK no problem
Problem starts with ASPX/asp.net.

Google showed some stupid webtutorial made by so called dev +/-10 yo. (based on voice). Complete crap.

Whats an equivalent of WebBrowser in ASPX/asp.net?

Not sure there is one, because asp.net is designed to run in a browser. Why run a browser in a browser. Put html in a div or iframe (depending on what you have) and you're good to go.

commented: Im just coding it for learning purpose +1