Hey, I wanted to find the stack on which a certain website is built? What are the tools that I can use? Wappalyzer isn't of much help. Want to know the stack and the CMS if any. Can anyone help?

Builtwith is an option.

You can check the response headers for some backend info.

Like VB said, BuiltWith.com is great. It does a bunch of things like scan DNS, looks at headers, standard admin pages etc

Shodan.io is a reverse option if you ever wondered