Look up the ASN, organization, and network prefix for any IPv4 or IPv6 address. Powered by MaxMind's GeoLite2-ASN database. Includes datacenter and hosting classification to identify residential vs. cloud traffic. Developer JSON API included.
Enter any IPv4 or IPv6 address to find its Autonomous System
An Autonomous System Number (ASN) is a globally unique identifier assigned to a group of IP prefixes managed by one or more network operators under a single, clearly defined routing policy. The internet is not one network — it is tens of thousands of autonomous systems exchanging routing information with each other using the Border Gateway Protocol (BGP).
When your browser sends a request to a server, BGP tables built from ASN announcements determine the path your packets take across the internet. Each ASN announces the IP prefixes it "owns" to neighboring networks, and routers worldwide use this information to forward traffic to the right destination.
ASNs are assigned by the five Regional Internet Registries (RIRs): ARIN (North America), RIPE NCC (Europe/Middle East/Central Asia), APNIC (Asia-Pacific), LACNIC (Latin America), and AFRINIC (Africa). An organization typically applies for an ASN when it operates a network that exchanges routing information with two or more upstream providers (multi-homing), or when it provides transit to other networks.
ASNs use BGP to announce IP prefixes they own to neighboring networks, building the global internet routing table.
ARIN, RIPE NCC, APNIC, LACNIC, and AFRINIC assign ASNs to organizations in their respective geographic regions.
Datacenter ASNs (AWS, DigitalOcean) often indicate VPN or proxy usage. Residential ASNs signal genuine end-user traffic.
Each ASN announces one or more IP prefixes (CIDR blocks) it controls, from small /24 blocks to massive /8 allocations.
Well-known Autonomous Systems operated by the world's largest internet organizations. Recognizing these ASNs helps classify traffic and build smarter fraud rules.
| ASN | Organization | Type | Region |
|---|---|---|---|
| AS15169 | Google LLC | Cloud / CDN | Global |
| AS13335 | Cloudflare, Inc. | CDN / DNS | Global |
| AS16509 | Amazon Web Services | Cloud | Global |
| AS8075 | Microsoft Corporation | Cloud / CDN | Global |
| AS32934 | Meta Platforms, Inc. | Cloud / Social | Global |
| AS20940 | Akamai Technologies | CDN | Global |
| AS14061 | DigitalOcean, LLC | Hosting / VPS | Global |
| AS63949 | Akamai Connected Cloud (Linode) | Hosting / VPS | Global |
| AS7922 | Comcast Cable Communications | ISP / Residential | North America |
| AS3215 | Orange S.A. | ISP / Residential | Europe |
| AS4134 | China Telecom | ISP / Residential | Asia-Pacific |
| AS174 | Cogent Communications | Tier-1 Transit | Global |
| AS3356 | Lumen Technologies (CenturyLink) | Tier-1 Transit | Global |
| AS9009 | M247 Europe SRL | VPN / Hosting | Europe |
Integrate ASN lookups into your application with a single GET request. Returns structured JSON with ASN number, organization, network prefix, and datacenter classification.
https://ip-api.io/api/v1/asn/{ip}
Returns ASN data for the given IPv4 or IPv6 address. Requires an API key for programmatic access. Cache-Control: 24 hours.
curl "https://ip-api.io/api/v1/asn/8.8.8.8?api_key=YOUR_API_KEY"import requests
response = requests.get(
"https://ip-api.io/api/v1/asn/8.8.8.8",
params={"api_key": "YOUR_API_KEY"}
)
data = response.json()
print(f"ASN: {data['asn']}, Org: {data['organization']}")
print(f"Network: {data['network']}, Datacenter: {data['is_datacenter']}")const response = await fetch(
"https://ip-api.io/api/v1/asn/8.8.8.8?api_key=YOUR_API_KEY"
);
const data = await response.json();
console.log(`AS${data.asn} — ${data.organization}`);
console.log(`Network: ${data.network}, Datacenter: ${data.is_datacenter}`);{
"ip": "8.8.8.8",
"asn": 15169,
"organization": "GOOGLE",
"network": "8.8.8.0/24",
"is_datacenter": true,
"country": "United States",
"country_code": "US"
}ip
string
Normalized IP address (IPv4 or IPv6)
asn
integer
Autonomous System Number (e.g. 15169 for Google)
organization
string
Organization name that operates the autonomous system
network
string
CIDR prefix block the IP belongs to (e.g. "8.8.8.0/24")
is_datacenter
boolean
True if the IP is in a known datacenter or hosting range
country
string
Country name for the IP address
country_code
string
ISO 3166-1 alpha-2 country code (e.g. "US")
400
Invalid IP address format
401
API key required or invalid
404
No ASN data found for this IP
429
Rate limit exceeded — slow down requests
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Common questions about Autonomous System Numbers and BGP routing
An Autonomous System Number (ASN) is a globally unique number assigned to a group of IP prefixes managed by one or more network operators under a single, coherent routing policy. ASNs are used in BGP (Border Gateway Protocol) to identify networks on the internet. Examples: AS15169 (Google), AS13335 (Cloudflare), AS16509 (Amazon Web Services).
Enter any IPv4 or IPv6 address into the lookup tool above and click "Look Up ASN." The tool
returns the ASN number, organization name, network prefix (CIDR), and whether the IP belongs to a
datacenter. For programmatic access, use GET https://ip-api.io/api/v1/asn/{ip}
with your API key.
An IP address identifies a single device (or NAT boundary) on the internet. An ASN identifies an entire network or group of networks operated by one organization. One ASN can encompass millions of IP addresses. IP addresses tell you where traffic goes; the ASN tells you who controls the network that routes that traffic.
ASNs are assigned by five Regional Internet Registries (RIRs) under the coordination of IANA: ARIN (North America), RIPE NCC (Europe, Middle East, Central Asia), APNIC (Asia-Pacific), LACNIC (Latin America & Caribbean), and AFRINIC (Africa). Organizations apply to their regional RIR when they need to exchange routing information with multiple upstream providers.
Yes. Large organizations often operate multiple ASNs for different regions, subsidiaries, or service categories. Amazon uses AS16509 for AWS, but also maintains several other ASNs for different parts of its infrastructure. Google, Meta, and Microsoft each operate dozens of ASNs globally. Each ASN represents a distinct autonomous system with its own routing policy.
ASN data reveals who controls the network an IP belongs to, which is a powerful fraud signal. Datacenter and hosting ASNs (DigitalOcean, AWS, Vultr) are frequently used by fraudsters to mask their location via VPNs or proxies. Legitimate users typically connect from residential ISP ASNs. Combine ASN classification with our Fraud Detection API for complete risk scoring.
BGP (Border Gateway Protocol) is the routing protocol that connects autonomous systems on the internet. Each ASN uses BGP to announce the IP prefixes it controls to neighboring networks. Routers worldwide maintain BGP tables built from these announcements, enabling them to forward packets to the correct destination across thousands of interconnected networks. BGP is often called "the protocol that holds the internet together."
Yes, the interactive ASN lookup tool on this page is completely free with no sign-up required.
Programmatic API access (GET /api/v1/asn/{ip}) requires a paid subscription.
Anonymous users can make limited requests via the tool directly from this page.
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