OpenGraph.to - Free Open Graph Checker & Preview Tool
WhatRuns – Discover What Runs a Website
Extensions: https://addons.mozilla.org/en-US/firefox/addon/whatruns/, https://chromewebstore.google.com/detail/whatruns/cmkdbmfndkfgebldhnkbfhlneefdaaip
WebSniffer
lychee
Bulk URL HTTP Status Code, Header & Redirect Checker
Wappalyzer - Find out what websites are built with
Visualping
What is my browser?
AboutUs
GWhois.org
urlscan.io
Host.io
FreeSiteStatus