ASN lookup
Look up an autonomous system by number, or find which AS announces an IP.
Queries are proxied through our server and never stored.
How to look up an ASN
- Choose what to look up. Enter an AS number (e.g. AS13335) or an IP address.
- Run the lookup. We query public routing data for the network details.
- Review. See the network name, country, registry and announced prefixes.
About autonomous systems
The internet is a network of networks, and each independently-routed network is an Autonomous System with its own number. ASNs are the unit of internet routing: BGP uses them to decide how traffic flows between providers. Looking one up tells you who operates a network, where it is registered, and how many address blocks it announces — useful for abuse reports, peering research, or simply understanding who is behind an IP. Start from an address with the IP address lookup, then drill into its network here.
Frequently asked questions
- An Autonomous System Number identifies a network that announces its own routes on the internet — typically an ISP, hosting provider or large organization. Example: AS13335 is Cloudflare.
- Enter an AS number to see its name, country, registry and prefix counts, or enter an IP address to find which AS announces it.
- From the public BGPView API, which aggregates routing and registry data. We proxy the request through our server so nothing about your query is stored.
- Prefixes are the IP address blocks an AS announces to the global routing table. The count gives a rough sense of the network’s size.
- IP lookup focuses on geolocation; ASN lookup focuses on the network and its routing. They complement each other.