Free tool · ASN data

ASN lookup

Enter an AS number to see who operates the network, where it is registered and which IP ranges it announces. The free lookup uses the ipbase ASN API, which is on the Small plan and above.

What is an ASN?

An autonomous system number identifies a network that has its own routing policy on the internet, such as a provider, cloud or large company.

Find the ASN of an IP

Use the IP lookup: it shows the ASN of any address.

Building this into an app? Use the ASN API and its ASN endpoint documentation.

ASN data by API

curl "https://api.ipbase.com/v2/asns?asn=AS13335" -H "apikey: YOUR-API-KEY"

Frequently asked questions

How do I find who owns an ASN?

Send the number, with or without the AS prefix, to the ASN endpoint of the ipbase API (Small plan and above). It returns the organization, its country and website, and the IP prefixes the network announces. For the ASN of a single IP address, use the free IP lookup.

What are some well-known ASNs?

AS15169 is Google, AS16509 Amazon (AWS), AS13335 Cloudflare, AS8075 Microsoft and AS32934 Meta (Facebook).

IP geolocation API

Get this data in your app

ipbase returns location, ISP, ASN and time zone for any IPv4 or IPv6 address, up to 1,000 addresses per POST request. Security flags (VPN, proxy, Tor, data center) are on the Small plan and above.

Read the documentation

150 free requests every month. No credit card required.

GET https://api.ipbase.com/v2/info?ip=1.1.1.1

{
  "data": {
    "ip": "1.1.1.1",
    "type": "v4",
    "connection": {
      "asn": 13335,
      "organization": "APNIC and Cloudflare DNS Resolver project",
      "isp": "Cloudflare, Inc",
      "range": "1.1.1.0/24"
    },
    "location": {
      "country": { "alpha2": "AU", "name": "Australia" },
      "zip": "4000"
    },
    "security": { "is_vpn": null, "is_tor": null, "threat_score": null }
  }
}

Free IP tools

Bulk IP lookup Up to 100 IPs at once, CSV export. IP address converter Decimal, hex, binary, IPv4↔IPv6. IP address lookup Location and owner of any IP. IP range to CIDR converter Ranges to CIDR blocks and back. Reverse IP lookup Domains hosted on any IPv4 address. Subnet calculator CIDR, netmask and host range. VPN and proxy checker VPN, proxy and Tor flags of any IP. What is my IP address? Your public IP, location and provider. What is my ISP? Which internet provider you use. Cloud & bot IP rangesOfficial lists of AWS, Googlebot, GPTBot and more.

Example lookups: 8.8.8.8 · 8.8.8.0/24 · AS15169 · example.com · all IPv4 ranges