netlupa

Network tools, free and with no sign-up

IP, DNS, WHOIS and subnet calculators in one place. Type what you need.

Your connection

What is my IPYour public IP, IPv4 and IPv6, with your provider and approximate location.IP lookupCountry, city, provider and coordinates of any public IP.

Network calculators

Subnet calculatorNetwork, broadcast, host range and mask of any IPv4, plus subnet splitting.VLSM calculatorSplit a network into subnets of different sizes without wasting addresses.IPv6 calculatorExpand and compress IPv6, get a prefix's range and split it into subnets.IP range to CIDRTurn IP ranges into CIDR blocks and merge lists of networks into the fewest blocks.

Domains and DNS

DNS lookupLook up a domain's A, AAAA, MX, TXT, NS, CNAME, SOA and CAA records.Domain and IP WHOISRegistrar, dates, nameservers and owner of a domain or an IP.SPF, DKIM and DMARC checkerCheck whether a domain's email is properly authenticated and why it may land in spam.SSL certificate checkerCheck a website's HTTPS certificate: validity, expiry, issuer and the names it covers.HTTP header checkerSee what a website returns: status code, redirects and security headers.

Converters and utilities

IP address converterConvert an IP to decimal, binary, hexadecimal or octal, and back. IPv6 too.MAC address lookupFind the manufacturer of a network card from its MAC address and spot random MACs.

Guides

What is CIDRThe /24 notation, how to work out a network's size and what it is for.IP address classesClasses A, B, C, D and E, their ranges and why they are rarely used today.IPv4 vs IPv6The differences between the two IP versions and how they coexist today.Public vs private IPThe difference between your router's IP and your devices' IPs.

What you can do with Netlupa

Netlupa brings together the most searched-for network tools, built both for people who just want to know their IP and for system administrators and networking students:

  • Your connection: see your public IP (IPv4 and IPv6) and locate any IP with its country, city and provider.
  • Calculators: IPv4 subnets with mask and CIDR, VLSM allocation, IPv6 prefixes and range-to-CIDR conversion.
  • Domains: DNS records (A, MX, TXT…), WHOIS, email authentication (SPF, DKIM and DMARC), SSL certificates and HTTP headers.
  • Utilities: IP to decimal, binary or hex converter and MAC address vendor lookup.

And, to understand what is behind them, guides with examples on CIDR, IP classes, IPv4 vs IPv6 and public vs private IPs. Everything is free, with no sign-up, and works just as well on your phone as on your computer.

No middlemen, and we don't keep your lookups

The calculators run on our server without going out to the internet. DNS lookups are answered by our own resolver, which asks each domain's official servers directly, and WHOIS data is requested straight from the registry of each domain or IP. Geolocation is computed with our own database.

We do not store what you look up or link it to you.

Frequently asked questions

Are the tools free?

Yes. Every tool is free, with no sign-up and no limits for reasonable use. The site is supported by advertising.

Do you store what I look up?

No. We use your IP and what you type only to give you the answer and, for one minute, to limit the number of lookups per person and prevent abuse.

Can I use them on my phone?

Yes. They work in any modern browser on your phone, tablet or computer, with nothing to install.