100K+ ASNs tracked — BGP data updated hourly

ASN Lookup

Get detailed Autonomous System Number data for any IP address or ASN. Uncover network ownership, routing prefixes, peer relationships, and organization details in one API call.

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100K+

ASNs tracked

BGP

Real routing data

4.2B

IPs covered

<100ms

Response time

Overview

What is an ASN?

An Autonomous System Number (ASN) is a unique identifier assigned to a network or group of IP prefixes operated by a single organization with a unified routing policy. ASNs are fundamental to how the internet routes traffic using BGP (Border Gateway Protocol).

HostInfo's ASN API maps any IP address or ASN number to rich organizational data — who owns the network, what IP ranges they control, what peers they have, and whether it's an ISP, hosting provider, or educational institution.

Lookup by IP or direct ASN number
Full BGP peer and prefix data
ASN type classification: ISP / hosting / edu
Historical ASN data included in Max tier

Sample Response

{
  "ip": "8.8.8.8",
  "asn": "AS15169",
  "asn_name": "GOOGLE",
  "asn_type": "hosting",
  "route": "8.8.8.0/24",
  "country": "US",
  "domain": "google.com",
  "num_ips": 4718592
}

Capabilities

Key Features

Deep BGP and network intelligence for every ASN on the internet.

Full BGP Routing Data

Access complete BGP routing tables including announced prefixes, route origins, and AS path data sourced from global route collectors.

Peer Relationships

See upstream and downstream BGP peers for any ASN. Understand connectivity and identify transit providers or potential network dependencies.

ASN Type Classification

Every ASN is classified as ISP, hosting provider, educational, government, or enterprise — enabling intelligent routing decisions and fraud logic.

IP Prefix Lists

Get all IP prefixes (CIDR ranges) announced by an ASN. Useful for building firewall rules, blocklists, or monitoring specific networks.

Historical ASN Data

Access historical prefix announcements and ownership changes — invaluable for incident response and threat research investigations.

Organization Details

Full organization name, country, registered domain, abuse contact, and RIR (Regional Internet Registry) for every ASN.

Reference

Data Fields

Every field available in the ASN Lookup API response.

Field	Type	Description	Free	Pro	Max
asn	string	ASN in "AS#####" format (e.g. "AS15169")	✓	✓	✓
asn_name	string	Organization name registered with the RIR	✓	✓	✓
asn_type	string	Classification: isp / hosting / edu / gov / enterprise	✓	✓	✓
route	string	BGP route/prefix the queried IP belongs to	✓	✓	✓
country	string	Country where the ASN is registered	✓	✓	✓
domain	string	Primary domain associated with the organization	—	✓	✓
num_ips	integer	Total number of IP addresses in the AS	—	✓	✓
peers	array	List of BGP peer ASNs	—	—	✓
prefixes	array	All announced IPv4 and IPv6 CIDR prefixes	—	—	✓

Try It Now

Live Demo

Enter any IP address or ASN to see network data instantly.

Try:

// Click "Lookup" to see results here...

Applications

Use Cases

How security and infrastructure teams use ASN data every day.

🔬

Network Security Analysis

Identify which ASN originates suspicious traffic. Block entire provider networks when abuse patterns emerge, and track threat actors by their infrastructure ASN.

🏢

Identify Hosting Providers

Instantly tell whether traffic comes from a residential ISP, a cloud datacenter, or a CDN — critical for distinguishing real users from bots and scrapers.

🕸️

Competitor Infrastructure Research

Map competitor infrastructure by tracing their IP ranges and ASN relationships. Understand scale, geographic footprint, and hosting partnerships from public routing data.

Developer

API Example

Query any IP or ASN and get structured network data back instantly.

curl -X GET \
  "https://api.hostinfo.com/v1/ip/8.8.8.8/asn" \
  -H "Authorization: Bearer YOUR_API_KEY"

# Response:
{
  "ip": "8.8.8.8",
  "asn": "AS15169",
  "asn_name": "GOOGLE",
  "asn_type": "hosting",
  "route": "8.8.8.0/24",
  "domain": "google.com"
}

const res = await fetch(
  'https://api.hostinfo.com/v1/ip/8.8.8.8/asn',
  { headers: { 'Authorization': 'Bearer YOUR_API_KEY' } }
);
const data = await res.json();
console.log(data.asn);       // "AS15169"
console.log(data.asn_name);  // "GOOGLE"
console.log(data.asn_type);  // "hosting"

import requests

r = requests.get(
    "https://api.hostinfo.com/v1/ip/8.8.8.8/asn",
    headers={"Authorization": "Bearer YOUR_API_KEY"}
)
data = r.json()
print(data["asn"])       # AS15169
print(data["asn_name"])  # GOOGLE
print(data["asn_type"])  # hosting