You should look at https://siftery.com/, it's nice :)

Thanks for asking this question. I never thought about it. I just use chrome dev tools and thought that was all there was.

what about stackshare it one of my favorites, you can check some of others known companies stacks at http://stackshare.io/stacks

Why do you try to copy some company's stack? They have their own requirements and reasons why they decided to use that particular software.

You should, rather than copying, take your needs and decide based on that what kind of stacks you want to play around with.

BuiltWith - is another service that provides a great overview of what different websites are build with. Information like:

• Nameserver Providers
• SSL Certificate, Email Services
• Hosting Providers
• Content Management Systems
• Frameworks
• Analytics and Tracking
• JavaScript Libraries
• Payment Providers
• CDNs
• Mapping
• Document type Information
• Server Information
• CSS Media Queries and Encoding, etc.

It's not 100% accurate, but it's closer than any other service I've used. Here is the result when I tried to search Hashnode.

P.S You can easily combine it with Wappalyzer, mentioned by @dhayanandhan.

You could use https://wappalyzer.com/ which predicts the tech stack of the website. I use wappalyzer chrome extension to quickly find out the tech behind a website.

This tool can't predict the server stack if they remove all headers though.