JPKCom DB

IP Tools

IPv4 and IPv6 in the browser: subnet calculator, range ↔ CIDR, address converter with reverse DNS, ULA generator, IANA special ranges, and your current IP.

A toolkit for IPv4 and IPv6

The IP Tools bundle six network helpers in one interface: they show your current IP address, calculate IPv4 and IPv6 subnets, turn address ranges into CIDR blocks, convert IP addresses between every common notation, generate private IPv6 addresses (ULA), and let you look up reserved ranges, address classes, and CIDR values in clear tables. Every address is classified against the IANA Special-Purpose Registries — the official lists of reserved IPv4 and IPv6 ranges. No account, no installation, no reaching for ipcalc on the command line — everything runs right in the browser.

The tool is built for everyone who works with networks: admins and network engineers who need to break down a subnet fast or get a firewall rule as a CIDR list; developers who want to turn an IP into an integer or make sense of IPv4-mapped IPv6 notation; and anyone who wants a handy reference with concrete examples while learning subnetting, CIDR, and IPv6.

The six tabs at a glance

The tool's interface is in English, so the tab names below match what you see on screen:

  • My IP — shows your current, server-detected IP address along with its classification (public, private, loopback, CGN …), version (IPv4/IPv6), conversions, and any detected proxy headers.
  • Subnet Calc — breaks an IPv4 network with a CIDR prefix or subnet mask down into network and broadcast address, host range, mask, wildcard mask, and host count, including a binary breakdown and subnet splits. It handles IPv6 prefixes such as 2001:db8:abcd::/48 too: first and last address, address count, the number of /64 networks, and the split into /52, /56, /60, and /64.
  • Converter — turns an IPv4 or IPv6 address into every common notation: hexadecimal, binary, integer, IPv4-mapped IPv6, NAT64, 6to4, the reverse DNS name (in-addr.arpa/ip6.arpa), and more. Teredo addresses are decoded into the server and client IPv4.
  • IPv6 ULA — generates a private IPv6 address (Unique Local Address) per RFC 4193 with a cryptographically random Global ID.
  • IP Range — translates any start/end range into the minimal list of covering CIDR blocks, and a CIDR prefix into the full address range it covers, for both IPv4 and IPv6.
  • Reference — lookup tables for reserved IPv4/IPv6 ranges (including benchmarking, Teredo, and the documentation prefix 3fff::/20), the classic network classes, a complete IPv4 CIDR table, and concise notes on CIDR, NAT, VLSM, and friends.

All calculated in the browser

With one exception, the tool is fully client-side: the subnet calculator, the converter, the ULA generator, the range calculator, and the CIDR table all compute purely in JavaScript in your browser. Nothing is sent to a server, nothing is stored, and there's no external API. The math runs on BigInt, so even 128-bit IPv6 values stay exact. The random numbers for the ULA generator come from your browser's crypto function (crypto.getRandomValues).

The only exception is the My IP tab: a browser can't technically know its own public IP — it lives in the request the server sees. So a small piece of server-side PHP reads it from the request (including any proxy headers) and reflects it back to you. That's not tracking: you're only shown what your own request transmits anyway.

Try it now

→ Open the IP Tools — pick a tab, enter an address, copy the result. No account, free, right in the browser. The calculation tabs come with clickable example values so you see a result immediately, and the ULA tab generates a first prefix as soon as you open it.

There's more on the subpages: the manual with every tab and output field in detail, examples for typical calculations, and a collection of tips & tricks on subnetting, CIDR, and IPv6.