Tools for domains, DNS & uptime

Handy DNS, email, network and monitoring utilities — free, no signup required.

DNS & Email

Look up A, AAAA, MX, TXT, NS, CNAME and CAA records for any domain.

Check the mail servers (MX records) a domain uses to receive email.

Build a valid SPF record to stop spammers spoofing your domain.

Generate a DMARC record to protect your domain from phishing and spoofing.

Calculate network, broadcast, host range and usable hosts from a CIDR.

Turn an uptime SLA percentage into allowed downtime per day, month and year.

Check whether a website is up or down, right now, from the edge.

Verify a domain serves a valid, trusted HTTPS certificate.