asn-index

Daily-updated index of ASN → IP prefix mappings, available in JSON and LMDB formats. Built from ipverse/as-ip-blocks and published as GitHub Release assets.

Browser lookup

Browse and search ASNs interactively at lens.ipverse.net (powered by the same ipverse dataset).

Downloads

Format	URL
JSON	https://github.com/remnawave/asn-index/releases/latest/download/asn-prefixes.json
LMDB (tar.gz)	https://github.com/remnawave/asn-index/releases/latest/download/asn-prefixes-lmdb.tar.gz

Data format

asn-prefixes.json

A single JSON object where each key is an ASN number (as a string) and the value contains IPv4 and IPv6 prefix lists:

{
  "13335": {
    "ipv4": ["1.0.0.0/24", "1.1.1.0/24"],
    "ipv6": ["2400:cb00::/32", "2606:4700::/32"]
  },
  "15169": {
    "ipv4": ["8.8.8.0/24"],
    "ipv6": ["2001:4860::/32"]
  }
}

asn-prefixes.lmdb

An LMDB database with:

• Key: ASN number (number)
• Value: { ipv4: string[], ipv6: string[] } (MessagePack-serialized via lmdb-js)

Usage

JSON

import { readFileSync } from 'node:fs';

const data = JSON.parse(readFileSync('asn-prefixes.json', 'utf8'));

// Direct object lookup
const cloudflare = data['13335'];
console.log(cloudflare.ipv4); // ["1.0.0.0/24", ...]

// Convert to Map for repeated lookups
const asnMap = new Map(Object.entries(data));
console.log(asnMap.get('13335').ipv6);

LMDB

import { open } from 'lmdb';

// Extract asn-prefixes-lmdb.tar.gz first, then:
const db = open({
  path: './asn-prefixes.lmdb',
  encoding: 'msgpack',
  readOnly: true,
});

const cloudflare = db.get(13335);
console.log(cloudflare.ipv4); // ["1.0.0.0/24", ...]

db.close();

Update frequency

The index is rebuilt daily at 04:00 UTC via a scheduled GitHub Actions workflow. Each run downloads the latest snapshot from ipverse/as-ip-blocks and overwrites the latest release assets.

Data source

IP prefix data is sourced from ipverse/as-ip-blocks, which aggregates routing data from public BGP sources.

License

MIT