HSTS Look Up

The HSTS (HTTP Strict Transport Security) look up fetches a domain over HTTPS and checks whether it sends a Strict-Transport-Security header telling browsers to only ever connect over HTTPS from now on.

Domain name

What do you want to look up?

Blacklist Look Up

Looks up whether this domain's IP address (or the IP address you entered) appears on common email blacklists (DNSBL) — being listed can cause outgoing mail to be rejected or sent to spam.

Also look up blacklist status when I run this search

How to use this tool

Pick a lookup type from the dropdown, or type a shortcut straight into the field — e.g. mx:example.com, all:example.com, spf:example.com, whois:example.com — and press Enter.
Enter a domain name (e.g. example.com), or an IP address for PTR and blacklist look ups.
Toggle "Also look up blacklist status" above to include a DNSBL look up alongside your search.
Your last 20 look ups are saved in the History panel so you can revisit them anytime.