Free IPv4 lookup — owner, ASN, geolocation, PTR
The complete IPv4 address space, mapped
Find the owner, ASN, country, state/region, city, reverse DNS, PTR records, and allocation history of any of the 4.3 billion IPv4 addresses. Search by IP, CIDR, ASN, organization, country, state, or city. No signup, no API key.
IPv4 allocation by country
Click any country to drill in. Colors scale logarithmically.
Browse the database
Top countries by IPv4 space →
- 1 United States 1,619.88M
- 2 China 350.07M
- 3 Japan 203.19M
- 4 Germany 140.22M
- 5 United Kingdom 138.06M
- 6 South Korea 123.21M
- 7 France 91.92M
- 8 Brazil 90.12M
- 9 Canada 73.82M
- 10 Italy 59.59M
Top states / regions
Top cities
Top organizations →
- 1 United States Department of Defense DoD 287.78M
- 2 Amazon.com, Inc. 173.65M
- 3 AT&T Enterprises, LLC 102.94M
- 4 Chinanet 101.00M
- 5 Verizon Business 87.17M
- 6 Comcast Cable Communications, LLC 68.31M
- 7 Microsoft Corporation 67.25M
- 8 CHINA UNICOM China169 Backbone 57.23M
- 9 Korea Telecom 46.42M
- 10 SoftBank Corp. 40.24M
Recent lookups
From the blog
All posts →What you can do here
- → IP address lookup — enter any IPv4 address (like 8.8.8.8) to see who owns it, their ASN, city, country, and reverse DNS.
- → CIDR range lookup — understand how IP space is carved into subnets. Browse 8.8.8.0/24 to see all 256 IPs in Google's DNS block.
- → ASN (autonomous system) lookup — trace BGP-routed prefixes back to their operator. AS15169 = Google. AS13335 = Cloudflare.
- → Organization IP footprint — see every CIDR block an organization owns and which countries they operate in.
- → Country, state, and city breakdown — drill from 250 countries down through 3,000+ states/regions into 120,000+ cities to see top ISPs and IP allocations at every level.
- → IPv4 exhaustion tracking — see how much of the 4.3B IPv4 address space is allocated and the RIR-by-RIR breakdown.
How WorldIP.io works
WorldIP.io merges three authoritative IPv4 datasets — MaxMind GeoLite2 for city-level geolocation, RIR delegation files (ARIN, RIPE, APNIC, LACNIC, AfriNIC) for allocation ownership, and Team Cymru for ASN-to-organization mapping.
Every IPv4 address gets its own deep-linkable URL. When you visit /1.1.1.1, we look up the range containing that IP, show the owner (Cloudflare), the ASN (AS13335), the BGP-routed prefix, the MaxMind geolocation, the reverse DNS record, and the 16 neighboring IPs in the same /24 — all cross-linked.
Data refreshes weekly from MaxMind. Learn more on our data sources page or browse the FAQ.
Frequently Asked Questions
What is an IPv4 address?
An IPv4 address is a 32-bit numeric identifier assigned to every device connected to the internet. Written as four numbers separated by dots (e.g., 8.8.8.8), there are approximately 4.3 billion possible IPv4 addresses. Each one is allocated to an organization, ISP, or government entity.
How do I look up who owns an IP address?
Enter any IPv4 address in the search bar above. WorldIP.io shows the owning organization, ASN (Autonomous System Number), geographic location, CIDR range, and reverse DNS record for every allocated IPv4 address.
What is an ASN?
An Autonomous System Number (ASN) identifies a network that independently manages its own routing policy. ISPs, cloud providers, and large enterprises each have one or more ASNs. WorldIP.io tracks over 79,259 active ASNs.
What is a CIDR range?
CIDR (Classless Inter-Domain Routing) notation like 8.8.8.0/24 describes a block of IP addresses. The number after the slash indicates how many addresses are in the block. A /24 contains 256 addresses, a /16 contains 65,536, and a /8 contains 16.7 million.
What is a reverse DNS (PTR) record?
A PTR record maps an IP address back to a hostname. For example, 8.8.8.8 resolves to dns.google. PTR records are used for email authentication (SPF/DKIM), network diagnostics, and identifying the services running on an IP address.
Is WorldIP.io free?
Yes. All IP lookups, searches, and data on WorldIP.io are completely free with no signup required. Our data is sourced from MaxMind GeoLite2, regional internet registries, and our own DNS scanning infrastructure.
