Free IP tools
Calculators for the address maths that comes up constantly and is tedious to do by hand. No sign-up, and every one of them runs locally — nothing you type leaves your browser. The one exception is bulk lookup, which has to call the API to answer at all, and says so on the page.
Addressing
- Subnet calculatorNetwork and broadcast address, subnet mask, wildcard mask, usable host range and host count for any IPv4 block.
- CIDR to IP rangeConvert a CIDR block to its first and last address, or collapse an arbitrary address range into the smallest set of CIDR blocks.
- IP in range checkerCheck whether an address falls inside a CIDR block or a first–last range, and see how two blocks relate to each other.
Conversion
- IP address converterConvert an IPv4 address between dotted-quad, decimal, hexadecimal, binary and octal.
- IPv6 expand & compressExpand an IPv6 address to its full 39-character form, or compress it to the canonical RFC 5952 short form.
- IPv4 to IPv6 converterSee an IPv4 address in every standard IPv6 form: IPv4-mapped, 6to4, NAT64 and the deprecated IPv4-compatible notation.
- Reverse DNS name generatorBuild the in-addr.arpa or ip6.arpa PTR name for any address, and list the reverse zones covering a whole block.
Generation
Reference
Bulk
Doing this for thousands of addresses?
These calculators run in your browser and never send us your input. When you need geolocation, ASN and network data for addresses in bulk, the API answers in one call — no key required to try it.
curl https://api.ipaddresstoday.com/api/v1/8.8.8.8