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
Wappalyzer - Find out what websites are built with
WebSniffer
lychee
Bulk URL HTTP Status Code, Header & Redirect Checker
AboutUs
FreeSiteStatus
GWhois.org
Host.io
urlscan.io
Visualping
What is my browser?