ASN Lookup
Find who holds an Autonomous System Number: organization, name, and country.
GuideGuide: How to Investigate a Suspicious IP Address in Your Client's LogsA fast, three-tool triage process — see how ASN Lookup fits alongside IP Lookup and Reverse DNS.GuideGuide: Is That Login Legit? How to Tell If an IP Is Coming Through a VPN or ProxyA client asking 'was that really me?' Use this tool alongside IP Lookup to check.GuideGuide: How to Quickly Vet a Suspicious Website Before You (or a Client) ClickCheck whether a suspicious link's hosting looks legitimate or disposable, alongside IP Lookup.
FAQ
What is an ASN?
An Autonomous System Number (ASN) identifies a network operator on the internet — an ISP, cloud provider, university, or company that manages its own routing policy. Every network large enough to run its own BGP routing has one.
What can I look up an ASN by?
Enter it with or without the "AS" prefix — both "AS15169" and "15169" work the same way.
Why can't I look up private-use ASNs?
Ranges like 64512–65534 and 4200000000–4294967294 are reserved for private/internal use (similar to private IP ranges) and aren't assigned to real public networks, so a registry lookup wouldn't return anything meaningful.