All tools
Free to use, no sign-up. We don’t log or store what you look up.
Email & DNS
Email security checkMX, SPF, DMARC, DKIM, MTA-STS, TLS-RPT, BIMI and DNSSEC for a domain in one go.MX lookupMail servers for a domain, their IP addresses and the likely email provider.DNS lookupA, AAAA, CNAME, MX, NS, TXT, SOA, CAA, SRV and more, with DNSSEC status.SPF checkerParses the SPF record, follows includes and counts DNS lookups against the limit of 10.DMARC checkerReads the DMARC policy, reporting addresses and alignment, and flags weak settings.DKIM lookupFinds DKIM keys by selector, or tries common selectors, and estimates key size.
IP & network
Reverse DNS (PTR)PTR record for an IPv4 or IPv6 address, and whether it resolves back (FCrDNS).Blacklist checkChecks an IP, or a domain’s mail servers, against public DNS blocklists.IP whois & ASNWho owns an IP address or AS number: network, organisation, country and abuse contact.What’s my IPYour public IP address as seen by this site.Certificate searchTLS certificates issued for a domain, from certificate transparency logs, with expiry dates.
Threat intel
Calculators
Subnet calculatorNetwork, broadcast, host range, mask and wildcard for an IPv4 subnet, and splitting it into smaller ones.CIDR & range toolTurn an IP range into CIDR blocks, merge a list of networks, or check if an IP is in a list.IPv6 toolExpand or compress an IPv6 address, find its prefix, type and reverse DNS name.Netmask & wildcard tableEvery prefix from /0 to /32 with its netmask, wildcard mask and host count.MAC address formatterConverts a MAC between formats, shows its flags and the EUI-64 IPv6 link-local address.Port referenceCommon TCP and UDP ports, what uses them, and whether they should face the internet.Password & PSK generatorStrong passwords, IPsec pre-shared keys and SNMP communities, generated in your browser.Timestamp converterUnix epoch to date and back, in UTC and your local time zone, for reading logs.
Review your firewall rules too
Paste a config from 12 firewall platforms — plus switches, Wi-Fi, NAC, Azure NSG, NetScaler, F5 and more — and get a graded review with fix commands, mapped to 16 standards. The config never leaves your browser.
Start free See a sample report