Read an autonomous system and its prefixes

The reverse of an address lookup's asn field: one autonomous system with the organisation operating it, the registry that allocated the number with the country and date it recorded, what the operator lists say about it (Spamhaus ASN-DROP, the curated satellite and mobile-carrier lists, tri-state like the address flags), and every prefix the DB-IP ASN database assigns to it — prefix_count per family is always whole, prefixes carries at most 500 per family and truncated says when it was cut. It is read from an index the server rebuilds from the ASN database once a month after it syncs; sources dates both.

A number the database assigns no prefix to — a reserved or private number, a system that has never held address space, a typo — answers 404 ASN_NOT_FOUND and costs nothing; a server that has not built the index yet answers 501 ASN_INDEX_UNAVAILABLE, also free. It is a fact about the database, not the registry: the RIR statistics may well have allocated the number.

curl https://spaw.co/api/v1/ip/asn/15169 \
  -H "Authorization: Bearer sk_live_…"

const response = await fetch('https://spaw.co/api/v1/ip/asn/15169', {
  method: 'GET',
  headers: {
    'Authorization': 'Bearer sk_live_…',
  },
});
const result = await response.json();

import requests

response = requests.get(
    'https://spaw.co/api/v1/ip/asn/15169',
    headers={'Authorization': 'Bearer sk_live_…'},
)
result = response.json()

$ch = curl_init('https://spaw.co/api/v1/ip/asn/15169');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => ['Authorization: Bearer sk_live_…'],
]);
$result = json_decode(curl_exec($ch), true);

from spaw import Client

client = Client('sk_live_…')
result = client.lookup_asn(15169)

import Spaw from 'spaw';

const spaw = new Spaw({ apiKey: 'sk_live_…' });
const result = await spaw.lookupAsn(15169);

use Spaw\Client;

$spaw = new Client('sk_live_…');
$result = $spaw->lookupAsn(15169);

{
    "success": true,
    "data": {
        "asn": 15169,
        "org": "Google LLC",
        "asn_type": "hosting",
        "registry": "arin",
        "registry_country": "US",
        "allocated_at": "2000-03-30",
        "is_blocklisted": false,
        "blocklist": null,
        "is_satellite": false,
        "is_mobile": false,
        "prefix_count": {
            "ipv4": 157,
            "ipv6": 28
        },
        "prefixes": {
            "ipv4": [
                "8.8.4.0/24",
                "8.8.8.0/24",
                "8.34.208.0/20",
                "8.35.192.0/20",
                "34.4.0.0/14"
            ],
            "ipv6": [
                "2001:4860::/32",
                "2404:6800::/32",
                "2607:f8b0::/32",
                "2800:3f0::/32",
                "2a00:1450::/32"
            ]
        },
        "truncated": false,
        "sources": [
            {
                "dataset": "asn-prefixes",
                "version": "2026-09-12"
            },
            {
                "dataset": "dbip-asn-lite",
                "version": "2026-09"
            },
            {
                "dataset": "rir-allocations",
                "version": "2026-09-12"
            },
            {
                "dataset": "threat-blocklists",
                "version": "2026-09-12"
            },
            {
                "dataset": "satellite-asns",
                "version": "2026-09-12"
            },
            {
                "dataset": "mobile-carrier-asns",
                "version": "2026-09-12"
            }
        ]
    },
    "meta": {
        "credits_used": 1,
        "credits_remaining": 8,
        "cache_hit": false,
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}

{
    "success": false,
    "error": {
        "code": "UNAUTHENTICATED",
        "message": "Provide a valid API key as a bearer token.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}

{
    "success": false,
    "error": {
        "code": "INSUFFICIENT_CREDITS",
        "message": "Your credit balance is empty.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}

{
    "success": false,
    "error": {
        "code": "ASN_NOT_FOUND",
        "message": "No autonomous system numbered 999999 is in the index.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}

{
    "success": false,
    "error": {
        "code": "RATE_LIMITED",
        "message": "Too many requests. Retry after the limit resets.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}

{
    "success": false,
    "error": {
        "code": "ASN_INDEX_UNAVAILABLE",
        "message": "The ASN prefix index has not been built on this server yet.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}