ASN Lookup Tool

Look up any Autonomous System Number for its owner, organization, country, and IP range count — the same ASN data returned by every IP lookup on ipto, free with no signup.

Enter an ASN above and press Look up.

An Autonomous System Number identifies a network that independently controls its own routing policy on the internet — an ISP, a cloud provider, a university, a single large company. Every IP address on the public internet is announced by exactly one ASN, which is how internet backbone routers know where to forward traffic.

What you get

Name & org: The short registry name (e.g. GOOGLE) and the full registered organization name (e.g. Google LLC).
Country: The country the ASN is registered in — not necessarily where every IP in its ranges is physically located, especially for large multinational networks.
Type: Category of the operating organization: hosting, ISP, business, education, government, mobile, or residential.
IP range count: How many distinct IP ranges are currently announced under this ASN in our dataset.

Use cases

ASN lookups are the fastest way to answer who actually owns a network — faster than WHOIS for routing-level questions, and the basis for VPN provider attribution, hosting-vs-residential classification, and abuse-network grouping elsewhere on this site.

FAQ

What's the difference between an ASN lookup and an IP lookup?

An IP lookup (/v1/ip/:ip) tells you about one address. An ASN lookup tells you about the entire network that address belongs to — useful once you already have the ASN from a prior IP lookup and want the owner's full details.

Can I search by company name instead of ASN number?

Not yet — this tool takes an ASN number only (with or without the "AS" prefix). If you have an IP and want its ASN, run it through the IP lookup first.

Is this the same data as the API?

Yes — this page is a thin UI over GET /v1/asn/:asn, documented in full on the API reference.

Can I see an ASN's peers, upstreams, and IP ranges?

Yes — the results page lists the ASN's IP ranges, RIR registration (whois), peering relationships (peers, upstream providers, and downstream customers from CAIDA's dataset), and related ASNs likely run by the same organisation. Each is also available as its own API endpoint under /v1/asn/:asn/.

About this tool

An Autonomous System Number (ASN) identifies a network that is run by a single organization and announces its own routes on the internet, such as an ISP, a cloud provider, a university or a large company. This tool takes an ASN, for example AS15169, and returns the registered owner, the organization name, its country and the number of IP ranges attributed to it.

How it works

Lookups are answered from ipto's own routing and registry dataset, which is refreshed on a daily schedule, so you get a result without waiting on a third-party API. Each result links to a dedicated page for that ASN listing its announced ranges and related networks, which makes it easy to move from a single address to the whole network behind it.

What to keep in mind

ASN ownership describes who operates a network, not who is using an individual address inside it. Registry records can lag behind real-world changes such as acquisitions, and country is the registration country, which is not always where the infrastructure physically sits.

Common uses

Typical uses include working out whether traffic comes from a hosting provider or a residential ISP, investigating an abusive source, tuning allow and block lists by network instead of by single address, and checking who a peer or upstream really is.