What is an ASN, and how to find yours

An ASN (Autonomous System Number) is the globally unique ID of a network on the internet. When an IP lookup shows AS13335 · Cloudflare, Inc., that AS13335 is the number identifying the network the address belongs to — one level up from the individual IP. To find yours, run curl ipconfig.io/asn.

Maintained by the ipconfig.io team · Reviewed 17 June 2026

What is an Autonomous System?

An Autonomous System (AS) is a network that controls its own routing under a single administrative policy. The internet isn't one network — it's a mesh of roughly 79,000 autonomous systems visible in the global routing table (CIDR Report, June 2026) that agree to carry each other's traffic. Each one gets a globally unique AS number:

• Your ISP is an AS (e.g. Comcast, Vodafone).
• Cloud and CDN providers are ASes — Cloudflare is AS13335, Google is AS15169.
• Universities, banks, and large companies often run their own AS.

So an ASN answers the question "which network does this IP belong to?"

How do I find my ASN?

Request the asn or asn-org endpoint — number or name, as plain text:

curl ipconfig.io/asn          # AS13335
curl ipconfig.io/asn-org      # Cloudflare, Inc.

Or read both alongside everything else in the JSON record:

curl -s ipconfig.io/json | jq -r '"\(.asn) — \(.asn_org)"'
# AS13335 — Cloudflare, Inc.

How do I find the ASN for any IP address?

Append ?ip= to look up someone else's network instead of your own:

curl ipconfig.io/asn-org?ip=8.8.8.8    # Google LLC

Why does my ASN matter?

Your ASN is how the rest of the internet identifies and treats your traffic — not your individual IP. Three practical reasons it matters:

1. It reveals who really carries your traffic. On mobile or behind a VPN, the ASN often shows the actual upstream provider, not the brand on the box.
2. It's the unit of filtering. Abuse lists, geo rules, and bot defenses frequently act per-ASN, so the network your traffic exits from affects how sites treat you.
3. It's the unit of routing. BGP, the protocol that glues the internet together, advertises routes between AS numbers. The ASN is your network's address on that map.

How are AS numbers assigned?

The five Regional Internet Registries — ARIN, RIPE NCC, APNIC, LACNIC, and AFRINIC — allocate ASNs, the same bodies that hand out IP blocks. AS numbers were originally 16-bit (0–65535); RFC 6793 extended them to 32-bit (four-octet) numbers, so the full range is now 0–4294967295 and modern ASNs run well into the millions.

Frequently asked questions

What is an ASN? A globally unique number identifying an autonomous system — a network that runs its own routing, like an ISP or cloud provider. Cloudflare is AS13335.

How do I find my ASN? Run curl ipconfig.io/asn for the number or curl ipconfig.io/asn-org for the name. Add ?ip= to look up any other address.

What is the range of AS numbers? Originally 16-bit (0–65535); RFC 6793 extended them to 32-bit, so the full range is 0–4294967295.

Next steps

Look up your own network now with curl ipconfig.io/asn, see how to geolocate any IP with curl, or read the API reference for every field in the record.