Qualys [1][2] For testing SSL of publicly accessible sites. TestSSL.sh [3] for testing SSL of any site including private endpoints you can reach from your mach

Qualys [1][2] For testing SSL of publicly accessible sites. TestSSL.sh [3] for testing SSL of any site including private endpoints you can reach from your machine Only requires openssl and bash. SecurityHeaders [4] for testing what headers are missing from a website. URLScan [5] for diagnosing a websites behavior. bgp.he.net [6] for looking up information about an IP/AS Number/domain. Robtex [7] also for looking up information about IP/AS/domain as well as org mapping. WhatIsMyDNS [8] for checking DNS propagation re-run this 3 times as their probe timeouts are way too low. Old-school VirusTotal [9] for old browsers for scanning malware. WhoisDS [10] targeting newly registered domains. Mozilla TLS configuration tool [11] for setting up proper TLS/HTTPS configuration on Nginx, Apache, HAproxy, etc... Certificate Search [12] for cert transparency logs, certificate fingerprints and more. Thousand Eyes [13] free dashboard on a commercial site. DownDetector [14] for uptime of popular sites and services. EDNS Validator [15] for verification of your DNS EDNS support. Shodan [16] for looking up detected vulnerabilities of an IP. W3C Validator [17] for testing HTML/CSS. [1] - https://www.ssllabs.com/ssltest/ https://www.ssllabs.com/ssltest/ [2] - https://dev.ssllabs.com/ssltest/ https://dev.ssllabs.com/ssltest/ [3] - https://github.com/drwetter/testssl.sh https://github.com/drwetter/testssl.sh [4] - https://securityheaders.com/ https://securityheaders.com/ [5] - https://urlscan.io/ https://urlscan.io/ [6] - https://bgp.he.net/ https://bgp.he.net/ [7] - https://www.robtex.com/ https://www.robtex.com/ [8] - https://www.whatsmydns.net/ https://www.whatsmydns.net/ [9] - https://www.virustotal.com/old-browsers/ https://www.virustotal.com/old-browsers/ [10] - https://www.whoisds.com/ https://www.whoisds.com/ [11] - https://ssl-config.mozilla.org/ https://ssl-config.mozilla.org/ [12] - https://crt.sh/ https://crt.sh/ [13] - https://www.thousandeyes.com/outages/ https://www.thousandeyes.com/outages/ [commercial site but priceless in my opinion] [14] - https://downdetector.com/ https://downdetector.com/ [15] - https://ednscomp.isc.org/ednscomp?zone=ycombinator.com https://ednscomp.isc.org/ednscomp?zone=ycombinator.com [16] - https://www.shodan.io/ https://www.shodan.io/ [17] - https://validator.w3.org/ https://validator.w3.org/