Skip to content
FizzKit

IP Address Lookup & Subnet Calculator

Parse and classify IPv4 and IPv6 addresses (private, CGNAT, loopback, link-local, multicast, documentation, ULA, Teredo, 6to4, NAT64), do full CIDR math for both versions including /31 point-to-point and /32 host routes, and look up the owning organisation, registry and allocation via RDAP (ARIN, RIPE, APNIC, LACNIC, AFRINIC). Reverse DNS, a "What’s my IP" button that shows the proxy header chain the relay saw, a bulk mode that classifies a pasted list with optional RDAP enrichment and CSV export, and CIDR helpers for containment checks, subnet splitting, range-to-CIDR and IPv4/IPv6 conversions.

Fetches URLs via the FizzKit relay — nothing is stored
IPv4 address
8.8.8.8
Public (globally routable)
Dotted decimal8.8.8.8
Integer134744072
Hex0x08080808
Binary00001000.00001000.00001000.00001000
ClassA
Reverse DNS name8.8.8.8.in-addr.arpa
IPv4-mapped IPv6::ffff:8.8.8.8
6to4 prefix2002:808:808::/48
Version
IPv4
Scope
Public
Bits
32
Prefix
—
RDAP
—
Reverse DNS
—

Related tools

URL Parser & Query Editor

Break any URL into parts, edit query params live, unwrap nested redirect URLs, decode ad macros, build UTMs and follow redirects.

User-Agent Parser

Parse any User-Agent — browsers, in-app webviews, CTV (Roku, Tizen, webOS, Fire TV), bots — merge Client Hints and get an OpenRTB device object.

Number Base Converter

Convert between binary, octal, decimal, hex and any base 2–36, with a bit grid, bitwise ops and IEEE-754.

HTTP Request Tester

Send GET, POST, PUT and other requests to any public URL and inspect status, headers, body, redirects and timing.

How to use IP Address Lookup & Subnet Calculator

  1. 1Paste an IP address, a CIDR block like 10.0.0.0/8, or a host:port such as [::1]:8080 — ports, brackets and zone ids are stripped automatically.
  2. 2Read the classification, integer/hex/binary forms and the subnet panel (network, broadcast, first/last host, usable hosts, /64 count for IPv6).
  3. 3Press Lookup (or ⌘Enter) to fetch the RDAP record and the reverse DNS name through the relay; click "raw JSON" to see the full registry response.
  4. 4Use "What’s my IP" to fill in your public address and see the X-Forwarded-For / CF-Connecting-IP chain the server received.
  5. 5Switch to Bulk to classify a pasted list, enrich it with RDAP organisations, and export CSV; use CIDR helpers for containment, splitting and range conversion.

About IP Address Lookup & Subnet Calculator

Parse and classify IPv4 and IPv6 addresses (private, CGNAT, loopback, link-local, multicast, documentation, ULA, Teredo, 6to4, NAT64), do full CIDR math for both versions including /31 point-to-point and /32 host routes, and look up the owning organisation, registry and allocation via RDAP (ARIN, RIPE, APNIC, LACNIC, AFRINIC). Reverse DNS, a "What’s my IP" button that shows the proxy header chain the relay saw, a bulk mode that classifies a pasted list with optional RDAP enrichment and CSV export, and CIDR helpers for containment checks, subnet splitting, range-to-CIDR and IPv4/IPv6 conversions.

IP Address Lookup & Subnet Calculator is part of FizzKit — a collection of focused developer and ad-tech tools. This tool uses the FizzKit relay to fetch public URLs on your behalf (so browser CORS rules do not get in the way); fetched content is returned to your browser and not stored.

Frequently asked questions

No. RDAP returns the registered organisation and country of the allocation, which is often not where the address is used. For city-level geolocation you need a commercial database.